Search results for: modifications for tyre wear

Authors: V. Pourmostaghimi, M. Zadshakoyan

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Efficiency and productivity of the finish hard turning can be enhanced impressively by utilizing accurate predictive models for cutting tool wear. However, the ability of genetic programming in presenting an accurate analytical model is a notable characteristic which makes it more applicable than other predictive modeling methods. In this paper, the genetic equation for modeling of tool flank wear is developed with the use of the experimentally measured flank wear values and genetic programming during finish turning of hardened AISI D2. Series of tests were conducted over a range of cutting parameters and the values of tool flank wear were measured. On the basis of obtained results, genetic model presenting connection between cutting parameters and tool flank wear were extracted. The accuracy of the genetically obtained model was assessed by using two statistical measures, which were root mean square error (RMSE) and coefficient of determination (R²). Evaluation results revealed that presented genetic model predicted flank wear over the study area accurately (R² = 0.9902 and RMSE = 0.0102). These results allow concluding that the proposed genetic equation corresponds well with experimental data and can be implemented in real industrial applications.

Keywords: cutting parameters, flank wear, genetic programming, hard turning

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Authors: Juan Carlos Baena, Zhongxiao Peng

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Ultra-high molecular weight polyethylene (UHMWPE) is extensively used in industrial and biomedical fields. The slippery nature of UHMWPE makes this material suitable for surface bearing applications, however, the operational conditions limit the lubrication efficiency, inducing boundary and mixed lubrication in the tribological system. The lack of lubrication in a tribological system intensifies friction, contact stress and consequently, operating temperature. With temperature increase, the material’s mechanical properties are affected, and the lifespan of the component is reduced. The understanding of how mechanical properties and wear performance of UHMWPE change when the temperature is increased has not been clearly identified. The understanding of the wear and mechanical performance of UHMWPE at different temperature is important to predict and further improve the lifespan of these components. This study evaluates the effects of temperature variation in a range of 20 °C to 60 °C on the hardness and the wear resistance of UHMWPE. A reduction of the hardness and wear resistance was observed with the increase in temperature. The variation of the wear rate increased 94.8% when the temperature changed from 20 °C to 50 °C. Although hardness is regarded to be an indicator of the material wear resistance, this study found that wear resistance decreased more rapidly than hardness with the temperature increase, evidencing a low material stability of this component in a short temperature interval. The reduction of the hardness was reflected by the plastic deformation and abrasion intensity, resulting in a significant wear rate increase.

Keywords: hardness, surface bearing, tribological system, UHMWPE, wear

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Authors: Paul Dallyn, Ashraf El-Hamalawi, Alessandro Palmeri, Bob Knight

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In order to better understand the long term implications of the grout wear failure mode in large-diameter plain-sided grouted connections, a numerical model has been developed and calibrated that can take advantage of existing operational plant data to predict the wear accumulation for the actual load conditions experienced over a given period, thus limiting the need for expensive monitoring systems. This model has been derived and calibrated based on site structural condition monitoring (SCM) data and supervisory control and data acquisition systems (SCADA) data for two operational wind turbine generator substructures afflicted with this challenge, along with experimentally derived wear rates.

Keywords: grouted connection, numerical model, offshore structure, wear, wind energy

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Authors: A. Mohammed, R. Lewis, M. Marshall

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Commonly used coatings to protect tools in die casting were used. A heat treatment and then surface coating can have a large effect on erosion damage. Samples have been tested to evaluate their resistances to erosive wear and to assess how this compares with behaviour seen for untreated material. Five commercial (PN + TiN), (PN + TiAlCN), (TiN X 2), (TiN), and (TiAlCN) coatings have been evaluated for their wear resistance. The objective was to permit an optimized selection of coatings to be used to give good resistance to erosive wear. A test-Rig has been developed to study the erosive wear in aluminium die casting and provide an environment similar to industrial operation that is more practical than using actual machines. These surfaces were analysed using a Scanning Electron Microscope (SEM) and Optical Microscopes each with a different level of resolution. Examination of coating materials revealed an important parameter associated with the failure of the coating materials.This was adhesion of the coating material to the substrate surface. A well-adhered coating withstands wear much better compared to the poorest-adhering coating.

Keywords: solid particle erosion, PVD-coatings, steel, erosion testing

Procedia PDF Downloads 246

Authors: Ammar Neshati, Elham Hamidi Shishavan

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Background and Aim: Enamel wear is among the main disadvantages of ceramic restorations. Recently, use of full zirconia crowns without dental porcelain has been suggested. The aim of this study was to compare the effect of feldspathic porcelain and zirconia on the wear of natural teeth. Materials and Methods: In this experimental study, 22 zirconia specimens were fabricated; out of which, 11 specimens were polished and used as zirconia specimens while the remaining 11 were used to fabricate porcelain specimens. A total of 22 natural human teeth were also collected. The natural teeth were photographed by a stereomicroscope in a fixed position and the distance from the cusp tip to a reference point was measured. Next, 11 teeth opposed zirconia and the remaining 11 opposed porcelain specimens in a chewing simulator and subjected to 120,000 masticatory cycles. The teeth were photographed again and the greatest difference between the before and after values was recorded. Results: The mean (± standard deviation) wear rate was 153.8±95.68 and 306.3±127.74, in the zirconia and porcelain groups, respectively; and the two groups had a statistically significant difference in this respect (P=0.007). Conclusion: The mean wear was significantly lower in teeth opposing zirconia than in those opposing feldspathic porcelain.

Keywords: natural tooth wear, feldspathic porcelain, zirconia, effect

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Authors: Fanyuan Shao, Wei Liu, Deli Gao

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Polycrystalline diamond composite (PDC) cutter is made of diamond powder as raw material, cobalt metal or non-metallic elements as a binder, mixed with WC cemented carbide matrix assembly, through high temperature and high-pressure sintering. PDC bits with PDC cutters are widely used in oil and gas drilling because of their high hardness, good wear resistance and excellent impact toughness. And PDC cutter is the main cutting tool of bit, which seriously affects the service of the PDC bit. The wear resistance of the PDC cutter is measured by cutting granite with a vertical turret lathe (VTL). This experiment can achieve long-distance cutting to obtain the relationship between the wear resistance of the PDC cutter and cutting distance, which is more closely to the real drilling situation. Load cell and 3D optical profiler were used to obtain the value of cutting forces and wear area, respectively, which can also characterize the damage and wear of the PDC cutter. PDC cutters were cut via electrical discharge machining (EDM) and then flattened and polished. A scanning electron microscope (SEM) was used to observe the distribution of binder cobalt and the size of diamond particles in a diamond PDC cutter. The cutting experimental results show that the wear area of the PDC cutter has a good linear relationship with the cutting distance. Simultaneously, the larger the wear area is and the greater the cutting forces are required to maintain the same cutting state. The size and distribution of diamond particles in the polycrystalline diamond layer have a great influence on the wear resistance of the diamond layer. And PDC cutter with fine diamond grains shows more wear resistance than that with coarse grains. The deep leaching process is helpful to reduce the effect of binder cobalt on the wear resistance of the polycrystalline diamond layer. The experimental study can provide an important basis for the application of PDC cutters in oil and gas drilling.

Keywords: polycrystalline diamond compact, scanning electron microscope, wear resistance, cutting distance

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Authors: Bharat Kumar, Deepak Kumar, Vijay Chaudhry

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Zirconium alloys are used as core components of nuclear reactors due to their high wear resistance, good corrosion properties, and good mechanical stability at high temperatures. Water flows inside the pressure tube through fuel claddings, which produces vibration of these core components and results in the wear of some components. Some components are subjected to the environment of coolant water containing LiOH which results in the corrosion of these components. The present work simulates some of these conditions to determine the failure mechanisms under these conditions and the effect of various parameters on them. Friction and wear experiments were performed varying the surrounding environment (room temperature, high temperature, and water submerged), duration, frequency, and displacement amplitude. Electrochemical corrosion experiments were performed by varying the concentration of LiOH in water. The worn and corroded surfaces were analyzed using scanning electron microscopy (SEM) to analyze the wear and corrosion mechanism and energy dispersive x-ray spectroscopy (EDS) and Raman spectroscopy to analyze the tribo-oxide layer formed during the wear and oxide layer formed during the corrosion. Wear increases with frequency and amplitude, and corrosion increases with LiOH concentration in water.

Keywords: zirconium alloys, wear, oxide layer, corrosion, EIS, linear polarization

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Authors: Rachit Marwaha, Rahul Dev Gupta, Vivek Jain, Krishan Kant Sharma

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Metal matrix hybrid composites (MMHCs) are now gaining their usage in aerospace, automotive and other industries because of their inherent properties like high strength to weight ratio, hardness and wear resistance, good creep behaviour, light weight, design flexibility and low wear rate etc. Al alloy base matrix reinforced with silicon carbide (10%) and graphite (5%) particles was fabricated by stir casting process. The wear and frictional properties of metal matrix hybrid composites were studied by performing dry sliding wear test using pin on disc wear test apparatus. Experiments were conducted based on the plan of experiments generated through Taguchi’s technique. A L9 Orthogonal array was selected for analysis of data. Investigation to find the influence of applied load, sliding speed and track diameter on wear rate as well as coefficient of friction during wearing process was carried out using ANOVA. Objective of the model was chosen as smaller the better characteristics to analyse the dry sliding wear resistance. Results show that track diameter has highest influence followed by load and sliding speed.

Keywords: Taguchi method, orthogonal array, ANOVA, metal matrix hybrid composites

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Authors: Md. Salim Kaiser

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In the present work, the effect of load and sliding distance on the performance tribology of commercially used aluminium-silicon engine block and piston was evaluated at ambient conditions with humidity of 80% under dry sliding conditions using a pin-on-disc with two different loads of 5N and 20N yielding applied pressure of 0.30MPa and 1.4MPa, respectively, at sliding velocity of 0.29ms-1 and with varying sliding distance ranging from 260m-4200m. Factors and conditions that had significant effect were identified. The results showed that the load and the sliding distance affect the wear rate of the alloys and the wear rate increased with increasing load for both the alloys. Wear rate also increases almost linearly at low loads and increase to a maximum then attain a plateau with increasing sliding distance. For both applied loads, the piston alloy showed the better performance due to higher Ni and Mg content. The worn surface and wear debris was characterized by optical microscope, SEM and EDX analyzer. The worn surface was characterized by surface with shallow grooves at loads while the groove width and depth increased as the loads increases. Oxidative wear was found to be the predominant mechanisms in the dry sliding of Al-Si alloys at low loads

Keywords: wear, friction, gravimetric analysis, aluminium-silicon alloys, SEM, EDX

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Authors: Mahmoudi Noureddine

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The glass fiber (GF) reinforced polyimide (PL) composites filled with graphite powders were fabricated by means of hot press molding technique. The friction and wear properties of the resulting composites sliding against GCr15 steel were investigated on a model ring-on-block test rig at dry sliding condition. The wear mechanisms were also discussed, based on scanning electron microscopic examination of the worn surface of the PL composites and the transfer film formed on the counterpart. With the increasing normal loads, the friction coefficient of the composites increased under the dry sliding, owing to inconsistent influences of shear strength and real contact areas. Experimental results revealed that the incorporation of graphite significantly improve the wear resistance of the glass fibers reinforced polyimide composites. For best combination of friction coefficient and wear rate, the optimal volume content of graphite in the composites appears to be 45 %. It was also found that the tribological properties of the glass fiber reinforced PL composites filled with graphite powders were closely related with the sliding condition such as sliding rate and applied load.

Keywords: composites, fiber, friction, wear

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Authors: H. K. Shivanand, A. Yogananda

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The objective of present investigation is to study the effect of reinforcements on the wear properties of E-Glass short fibers and Flyash reinforced Al 8011 hybrid metal matrix composites. The alloy of Al 8011 reinforced with E-glass and fly ash particulates are prepared by simple stir casting method. The MMC is obtained for different composition of E-glass and flyash particulates (varying E-glass with constant fly ash and varying flyash with constant E-glass percentage). The wear results of ascast hybrid composites with different compositions of reinforcements at varying sliding speeds and different loads are discussed. The results reveals that as the percentage of reinforcement increases wear rate will decrease.

Keywords: metal matrix composites, aluminum alloy 8011, stir casting, wear test

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Authors: Henrique Gomes dos Santos, Manoel Henrique Alves, Jane Zoppas Ferreira, Annelise Kopp Alves

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This work aimed to seek an environmentally sustainable surface coating alternative by researching the influence of the addition of graphene oxide (GO) and carbon nanotubes (CNT) on the silanization of coatings to increase the wear resistance in galvanized steel, using the pin-on-disk test. The results obtained were compared between different concentrations of additives and the number of coating layers, in addition to comparing with samples without coating and only with silane layers. Bis-1,2-(triethoxysilyl)ethane (BTSE) silane was used in silanizing the coatings with CNT or GO and applied to the samples through dip-coating to form one, four, or eight layers. The wear test results found that three samples stood out in relation to the objective, showing an increase in wear resistance compared to the galvanized sample only. The rolling effect and the lubricity character presented by carbon nanotubes were positive for the increase in wear resistance obtained. The reduction in wear compared to the galvanized-only sample reached 82%. Raman spectroscopy was also carried out to detect the presence of silane, GO, and CNT, in addition to roughness tests and SEM to assess the homogeneity of the coating. The carbonaceous additives, graphene oxide, and carbon nanotubes in certain amounts of layers and specific concentrations fulfilled their objective against the wear imposed on the substrate.

Keywords: silane, coating, graphene oxide, carbon nanotubes, wear resistance

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Authors: Hikmet Cicek

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Metal nitrides show excellence tribological properties and they used for especially on machine parts. In this work, the vacuum gas nitriding proses were applied to the titanium, D2 and 52100 steel substrates at three different proses temperatures (500 °C, 600°C and 700 °C). Structural, mechanical and tribological properties of the samples were characterized. X-Ray diffractometer, scanning electron microscope and energy dispersive spectroscopy analyses were conducted to determine structural properties. Microhardness test and pin-on-disc wear test were made to observe tribological properties. Coefficient of friction, wear rate and wear traces were examined comparatively. According to the test results, the process temperature very effective parameter for the vacuum gas nitriding method.

Keywords: gas nitriding, tribology, wear, coating

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Authors: Jie Chen, Chris Cheng, Kai Zhang

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Polycrystalline diamond compact (PDC) cutters with a polycrystalline diamond (PCD) table supported by a cemented tungsten carbide substrate have been widely used for earth-drilling tools in the oil and gas industry. Both wear and impact resistances are key figure of merits of PDC cutters, and they are closely related to the microstructure of the PCD table. As oil and gas exploration enters deeper, harder, and more complex formations, plus increasing requirement of accelerated downhole drilling speed and drilling cost reduction, current PDC cutters face unprecedented challenges for maintaining a longer drilling life than ever. Excessive wear on uneven hard formations, spalling, chipping, and premature fracture due to impact loads are common failure modes of PDC cutters in the field. Tailoring microstructure of the PCD table is one of the effective approaches to improve the wear and impact resistances of PDC cutters, along with other factors such as cutter geometry and bit design. In this research, cross-sectional microstructure, fracture surface, wear surface, and elemental composition of PDC cutters were analyzed using scanning electron microscopy (SEM) with both backscattered electron and secondary electron detectors, and energy dispersive X-ray spectroscopy (EDS). The microstructure and elemental composition were further correlated with the wear and impact resistances of corresponding PDC cutters. Wear modes and impact toughening mechanisms of state-of-the-art PDCs were identified. Directions to further improve the wear and impact resistances of PDC cutters were proposed.

Keywords: fracture surface, microstructure, polycrystalline diamond, PDC, wear surface

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Authors: Jagriti Mishra, Vasundhara Chaudhary

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Introduction: The case highlights various issues and challenges faced by Khanna Enterprises while conceptualizing and execution of launching Active Leisure wear in the domestic market, where different steps involved in the range planning and production have been elaborated. Although Khanna Enterprises was an established company which dealt in the production of knitted and woven garments, they took the risk of launching a new concept- Active Leisure wear for Millennials. Methodology: It is based on primary and secondary research where data collection has been done through survey, in-depth interviews and various reports, forecasts, and journals. Findings: The research through primary and secondary data and execution of active leisure wear substantiated the acceptance, not only by the millennials but also by the generation X. There was a demand of bigger sizes as well as more muted colours. Conclusion: The sales data paved the way for future product development in tune with the strengths of Khanna Enterprises.

Keywords: millennials, range planning, production, active leisure wear

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Authors: Mehmet Fahri Sarac, Gokcen Akgun

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Ti–6Al–4V alloys are widely used in biomedical industries because of its attractive mechanical and physicochemical properties. However, they have poor wear resistance. High velocity oxygen fuel (HVOF) coatings were investigated as a way to improve the wear resistance of this alloy. In this paper, different mass ratio of Al₂O₃-TiO₂ powders (60/40, 87/13 and 97/3) was employed to enhance the tribological properties of Ti–6Al–4V. The tribological behavior was investigated by wear tests using ball-on-disc and pin-on-disc tribometer. The microstructures of the contact surfaces were determined by a scanning electron microscopy before and after the test to study the wear mechanism. Uncoated and coated surfaces after wear test are also subjected to micro-hardness tests. The tribological test results showed that the microhardness, friction and wear resistance of coated Ti-6Al-4V alloys increases by increasing TiO₂ content in the powder composite when other experimental conditions were constant. Finally, Al₂O₃-TiO₂ powder composites for the investigated conditions, both coating samples had satisfactory values of friction and wear resistance, and they could be suitable candidates for Ti–6Al–4V material.

Keywords: HVOF (High Velocity Oxygen Fuel), Al₂O₃-TiO₂, Ti-6Al-4V, tribology

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Authors: David Robert Irvine

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In the dental restoration sector, there has been a shift to using zirconia. With the ever increasing need to decrease lead times to deliver restorations faster the zirconia is machined in its pre-sintered state instead of grinding the very hard sintered state. As with all machining, there is tool wear and while investigating the tooling used to machine pre-sintered zirconia it became apparent that the wear rate is based more on material build up and abrasion than it is on plastic deformation like conventional metal machining. It also came to light that the tool material can currently not be selected based on wear resistance, as there is no data. Different works have analysed the effect of the individual wear mechanism separately using similar if not the same material. In this work, the testing method used to analyse the wear was a modified from ISO 8688:1989 to use the pre-sintered zirconia and the cutting conditions used in dental to machine it. This understanding was developed through a series of tests based in machining operations, to give the best representation of the multiple wear factors that can occur in machining of pre-sintered zirconia such as 3 body abrasion, material build up, surface welding, plastic deformation, tool vibration and thermal cracking. From the testing, it found that carbide grades with low trans-granular rupture toughness would fail due to abrasion while those with high trans-granular rupture toughness failed due to edge chipping from build up or thermal properties. The results gained can assist the development of these tools and the restorative dental process. This work was completed with the aim of assisting in the selection of tool material for future tools along with a deeper understanding of the properties that assist in abrasive wear resistance and material build up.

Keywords: abrasive wear, cemented carbide, pre-sintered zirconia, tool wear

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Authors: Pankaj Kumar Das, Niranjan Kumar, Prasun Chakraborti

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Temperature dependent tribologiocal properties of nuclear grade turbostatic graphite were studied using 100Cr6 steel counterbody. High value of friction coefficient (0.25) and high wear loss was observed at room temperature and this value decreased to 0.1 at 150oC. Consequently, wear loss is also decreased. Such behavior is explained by oxidation/vaporization of graphite and water molecules. At room temperature, the adsorbed water in graphite does not decompose and effect of passivation mechanism does not work. However, at 150oC, the water decomposed into OH, atomic hydrogen and oxygen which efficiently passivates the carbon dangling bonds. This effect is known to decrease the energy of the contact and protect against abrasive wear.

Keywords: high temperature tribology, oxidation, turbostratic graphite, wear

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Authors: Shaleni Bajpai, Nancy Stephan

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Various designs of women’s kurtis with different styles, motifs and prints were available in market but none of the kurtis was found in army print. Mostly army prints are used for men’s wear like jackets, trousers, caps, bags. The main colours available in military prints were beige, parrot green, red, dark blue, light blue, orange, bottle green, pink and the original military green colour. As the original camouflage is banned in civil wears so the different variety and colours were used in this study to popularize army prints in women’s wear. The aim of this project was to construct different styles of women kurti’s with various colours of different military prints. Mood board, inspiration and colour board was prepared to design the kurtis. The fabric used for construction was army printed poplin and crepe. The designing and construction of kurti’s were divided into two categories such as - casual and party wear. Casual wear had simple silhouette like a-line, high-low and waist coat style whereas party wear included princess line, panelled and bandhani style. Structured questionnaire was prepared to assess the acceptance of newly designed kurtis with respect to colour combination, overall appearance and cost. Purposively sampling method was adopted for selection of respondents. Opinion was taken from 100 women of various age groups. The result and analysis was presented through graph and percentage. Kurtis in army print of both the categories were appreciated by the respondents.

Keywords: army, kurti, casual wear, party wear

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Authors: Antônio P. de Araújo Neto, Ruy D. A. da Silva Neto, Juliana R. de Souza, Salete K. P. de Medeiros, João T. N. de Medeiros

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The tribological test with Pin-On-Disc configuration measures friction and wear properties in dry or lubricated sliding surfaces of a variety of materials and coatings. Polymeric matrix composites loaded with mineral filler were used, 1%, 3%, 10%, 30%, and 50% mass percentage of filler, to reduce the material cost by using mineral tailings. Using a pin-on-disc tribometer to quantify coefficient of friction and wear resistance of the specimens. The parameters known to performing the test were 300 rpm rotation, normal load of 16N and duration of 33.5 minutes. The composite with 10% mineral filler performed better, considering that the wear resistance was good when compared to the other compositions and an average low coefficient of friction, in the order of μ ≤ 0.15.

Keywords: microcomposites, microparticles tailings of scheelite, PTFE, tribology

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Authors: Saad Nawaz, Yu Gang, Miao Haibin

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Titanium alloys are attractive materials for aerospace industry due to their exceptional strength to weight ratio that is maintained at elevated temperatures and their good corrosion resistance. Major applications of titanium alloys were military aerospace industry, but since last decade the trend has now shifted towards commercial industry. On the other hand, titanium alloys are notorious for being poor thermal conductor that leads to them being difficult materials for machining. In this experimental study, Stellram Indexable milling cutter XDLT09-D41 is used for rough down milling of Ti6Al4V for small depth of cut under different combinations of parameters and application of high-pressure coolant. The machining performance was evaluated in terms of tool wear, tool life, and thermal crack. The tool wear was mostly observed at the tool tip and at bottom part of tool thermal deformations were observed which propagated with respect to time. Flank wear due to scratching of the cutting chips and diffusion wear because of high thermal stresses were observed specially at the bottom of the cutting tool. It was found that maximum tool life was obtained at the speed of 40m/min, feed rate of 358mm/min and depth of cut of 0.8mm. In the end, it was concluded that machining of Ti6Al4V is a thermally dominant process which leads to high thermal stresses in machining zone that results in increasing tool wear rate and deformation propagation.

Keywords: tool wear, cutting speed, flank wear , tool life

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Authors: M. Hadji, A. Haddad, Y. Hadji

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The effects of boronizing treatment on the friction coefficient and wear behavior of Ti2AlC were investigated. In order to modify the surface properties of Ti2AlC, boronizing treatment was carried out through powder pack cementation in the 1150-1350 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB2 and SiC, forms on the surface of Ti2AlC. The growth of the coating is processed by inward diffusion of Boron and obeys a linear rule. The Boronizing treatment increases the hardness of Ti2AlC from 6 GPa to 13GPa. In the pin-on-disc test, it was found that the material undergoes a steady-state coefficient of friction of around 0.8 and 0.45 in case of Ti2AlC/Al2O3 tribocouple under 7N load for the non treated and the boronized samples, respectively. The wear resistance of Ti2AlC under Al2O3 ball sliding has been significantly improved, which indicated that the boronizing treatment is a promising surface modification way of Ti2AlC.

Keywords: MAX phase, wear, hardness, boronizing

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Authors: Mohammad Reza Koushki Ardestani, Saeed Daneshmand, Mohammad Heydari Vini

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In the present study, AA7075/SiO2 composites have been fabricated via liquid metallurgy process. Using the degassing process, the wet ability of the molten aluminum alloys increased which improved the bonding between aluminum matrix and reinforcement (SiO2) particles. AA7075 alloy and SiO2 particles were taken as the base matrix and reinforcements, respectively. Then, contents of 2.5 and 5 wt. % of SiO2 subdivisions were added into the AA7075 matrix. To improve wettability and distribution, reinforcement particles were pre-heated to a temperature of 550°C for each composite sample. A uniform distribution of SiO2 particles was observed through the matrix alloy in the microstructural study. A hardened EN32 steel disc as the counter face was used to evaluate the wear rate pin-on-disc, a wear testing machine containing. The results showed that the wear rate of the AA/SiO2 composites was lesser than that of the monolithic AA7075 samples. Finally, The SEM worn surfaces of samples were investigated.

Keywords: Al7075, SiO₂, wear, composites, stir casting

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Authors: Djeridi Rachid, Ould Ouali Mohand

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The search of a mechanism for the elastomer abrasive wear study is an open issue. The practice difficulties are complex due to the complexity of deformation mechanism, to the complex mechanism of the material tearing and to the marked interactions between the tribological parameters. In this work, we present an experimental technique to study the elastomers abrasive wear. The interaction 'elastomer/indenter' implicate dependant ant temporary of different tribological parameters. Consequently, the phenomenon that governs this interaction is not easy to explain. An optimal elastomers compounding and an adequate utilization conditions of these materials that define its resistance at the abrasion is discussed. The results are confronted to theoretical models: the weight loss variation in function of blade angle or in function of cycle number is in agreement with rupture models and with the mechanism of fissures propagation during the material tearing in abrasive wear of filler elastomers. The weight loss in function of the sliding velocity shows the existence of a critical velocity that corresponds to the maximal wear. The adding of silica or black carbon influences in a different manner on wear abrasive behavior of filler elastomers.

Keywords: abrasion wear, filler elastomer, tribology, hyperelastic

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Authors: Olawale S. Fatoba, Stephen A. Akinlabi, Esther T. Akinlabi, Rezvan Gharehbaghi

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The performance of material surface under wear and corrosion environments cannot be fulfilled by the conventional surface modifications and coatings. Therefore, different industrial sectors need an alternative technique for enhanced surface properties. Titanium and its alloys possess poor tribological properties which limit their use in certain industries. This paper focuses on the effect of hybrid coatings Al-Cu-Fe on a grade five titanium alloy using laser metal deposition (LMD) process. Icosahedral Al-Cu-Fe as quasicrystals is a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. A 3kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the cladding process was utilized for the fabrication of the coatings. The titanium cladded surfaces were investigated for its hardness, corrosion and tribological behaviour at different laser processing conditions. The samples were cut to corrosion coupons, and immersed into 3.65% NaCl solution at 28oC using Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization (LP) techniques. The cross-sectional view of the samples was analysed. It was found that the geometrical properties of the deposits such as width, height and the Heat Affected Zone (HAZ) of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminum and titanium presented in the formation of the composite. The indentation testing reveals that for both scanning speed of 0.8 m/min and 1m/min, the mean hardness value decreases with increasing laser power. The low coefficient of friction, excellent wear resistance and high microhardness were attributed to the formation of hard intermetallic compounds (TiCu, Ti2Cu, Ti3Al, Al3Ti) produced through the in situ metallurgical reactions during the LMD process. The load-bearing capability of the substrate was improved due to the excellent wear resistance of the coatings. The cladded layer showed a uniform crack free surface due to optimized laser process parameters which led to the refinement of the coatings.

Keywords: Al-Cu-Fe coating, corrosion, intermetallics, laser metal deposition, Ti-6Al-4V alloy, wear resistance

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Authors: L. Capitanu, V. Floresci, L. L. Badita

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Starting from the idea that the greatest pressure and velocity of composite melted is in the die nozzle, was an experimental nozzle with wear samples of sizes and weights which can be measured with precision as good. For a larger accuracy of measurements, we used a method for radiometric measuring, extremely accurate. Different nitriding steels have been studied as nitriding treatments, as well as some special steels and alloyed steels. Besides these, there have been preliminary attempts made to describe and checking corrosive action of thermoplastics on metals.

Keywords: plastics, composites with short glass fibres, moulding, wear, experimental modelling, glass fibres content influence

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Authors: Daniel Ferreira, José M. Marques Oliveira, Filipe Oliveira

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Wear phenomena is critical in injection moulding processes, causing failure of the components, and making the parts more expensive with an additional wasting time. When very abrasive materials are being injected inside the steel mould’s cavities, such as polymers reinforced with abrasive fibres, the consequences of the wear are more evident. Maraging steel (1.2709) is commonly employed in moulding components to resist in very aggressive injection conditions. In this work, the wear performance of the SLM produced 1.2709 maraging steel reinforced by ultrafine titanium and tungsten carbide (TiC-WC), was investigated using a pin-on-disk testing apparatus. A polypropylene reinforced with 40 wt.% fibreglass (PP40) disk, was used as the counterpart material. The wear tests were performed at 40 N constant load and 0.4 ms-1 sliding speed at room temperature and humidity conditions. The experimental results demonstrated that the wear rate in the 18Ni300-TiC-WC composite is lower than the unreinforced 18Ni300 matrix. The morphology and chemical composition of the worn surfaces was observed by 3D optical profilometry and scanning electron microscopy (SEM), respectively. The resulting debris, caused by friction, were also analysed by SEM and energy dispersive X-ray spectroscopy (EDS). Their morphology showed distinct shapes and sizes, which indicated that the wear mechanisms, may be different in maraging steel produced by casting and SLM. The coefficient of friction (COF) was recorded during the tests, which helped to elucidate the wear mechanisms involved.

Keywords: selective laser melting, nanocomposites, injection moulding, polypropylene with fibreglass

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Authors: M. Hadji, A. Haddad, Y. Hadji

Abstract:

The effects of boronizing treatment on the friction coefficient and wear behavior of 0.35 Vf TiC- Ti3 SiC2 composite were investigated. In order to modify the surface properties of Ti3SiC2, boronizing treatment was carried out through powder pack cementation in the 1150-1350 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB2 and SiC, forms on the surface of Ti3SiC2. The growth of the coating is processed by inward diffusion of Boron and obeys a linear rule. The Boronizing treatment increases the hardness of Ti3SiC2 from 6 GPa to 13 GPa. In the pin-on-disc test, i twas found that the material undergoes a steady-state coefficient of friction of around 0.8 and 0.45 in case of Ti3SiC2/Al2O3 tribocouple under 7 N load for the non treated and the boronized samples, respectively. The wear resistance of Ti3SiC2 under Al2O3 ball sliding has been significantly improved, which indicated that the boronizing treatment is a promising surface modification way of Ti3SiC2.

Keywords: MAX phase, boronizing, hardness, wear

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Authors: Mattahias Maj, Fabio Tatzgern, Karl Adam, Damir Kahrimanovic, Markus Varga

Abstract:

Torpedo ladles are necessary transport carriages in steel production to move the molten crude iron from the blast furnace to the steel refining plant. This requires the ladles to be high temperature resistant and insulate well to preserve the temperature and hold the risk of solidification at bay. Therefore, the involved refractories lining the inside of the torpedo ladles are chosen mostly according to their thermal properties, although wear of the materials by the liquid iron is also of major importance. In this work, we combined investigations of the thermal behaviour with wear studies of the lining over the whole lifetime of a torpedo ladle. Additional numerical simulations enabled a detailed model of the mechanical loads and temperature propagation at the various stations (heating, filling, emptying, cooling). The core of the investigation were detailed 3D measurements of the ladle’s cavity and thereby quantitative information of the wear progress at different time intervals during the lifetime of the ladles. The measurements allowed for a separation of different wear zones according to severity, namely the “splash zone” where the melt directly hits the ladle, the “melt zone” where during transport always liquid melt is present, and the “slag zone”, where the slag floats on the melt causing the most severe wear loss. Numerical simulations of the filling process were taken to calculate stress levels and temperature gradients, which led to the different onset of wear on those zones. Thermal imaging and punctual temperature measurements allowed for a study of the thermal consequences entailed by the wear onset. Additional “classical” damage analysis of the worn refractories complete the investigation. Thereby the wear mechanisms leading to the substantial wear loss were disclosed.

Keywords: high temperature, tribology, liquid-solid interaction, refractories, thermography

Procedia PDF Downloads 226

Authors: A. Mostaani, M. P. Pereira, B. F. Rolfe

Abstract:

The increasing application of Advanced High Strength Steel (AHSS) in the automotive industry to fulfill crash requirements has introduced higher levels of wear in stamping dies and parts. Therefore, understanding wear behaviour in sheet metal forming is of great importance as it can help to reduce the high costs currently associated with tool wear. At the contact between the die and the sheet, the tips of hard tool asperities interact with the softer sheet material. Understanding the deformation that occurs during this interaction is important for our overall understanding of the wear mechanisms. For these reasons, the scratching of a perfectly plastic material by a rigid indenter has been widely examined in the literature; with finite element modelling (FEM) used in recent years to further understand the behaviour. The ‘wear mode diagram’ has been commonly used to classify the deformation regime of the soft work-piece during scratching, into three modes: ploughing, wedge formation, and cutting. This diagram, which is based on 2D slip line theory and upper bound method for perfectly plastic work-piece and rigid indenter, relates different wear modes to attack angle and interfacial strength. This diagram has been the basis for many wear studies and wear models to date. Additionally, it has been concluded that galling is most likely to occur during the wedge formation mode. However, there has been little analysis in the literature of how the material behaviour and deformation conditions associated with metal forming processes influence the wear behaviour. Therefore, the first aim of this work is first to use a commercial FEM package (Abaqus/Explicit) to build a 3D model to capture wear modes during scratching with indenters with different attack angles and different interfacial strengths. The second goal is to utilise the developed model to understand how wear modes might change in the presence of bulk deformation of the work-piece material as a result of the metal forming operation. Finally, the effect of the work-piece material properties, including strain hardening, will be examined to understand how these influence the wear modes and wear behaviour. The results show that both strain hardening and substrate deformation can change the critical attack angle at which the wedge formation regime is activated.

Keywords: finite element, pile-up, scratch test, wear mode

Procedia PDF Downloads 327