Papers by Keyword: Abrasive Wear

Abstract: The aim of this research was to optimize the mechanically activated synthesis (MAS) technology of the Cr₃C₂-Ni powder intended for thermal spraying. The MAS production route included ball milling for 72 h (ball-to-powder ratio 20:1) and sintering under 1075 °C in vacuum for 4 h. Sintered compact was crushed, classified by sieving to obtain the fraction suitable for thermal spraying (20–45 μm). The morphology and the phase composition of the powder were analyzed by a scanning electron microscope (SEM) and X-ray diffraction (XRD). The optimal Cr:C ratio found was 7:1. The powder had an equiaxial or a slightly elongated lamellar shape, Cr₃C₂ carbides in a single powder particle had an elongated shape. The principal phases in the optimized powder were Cr₃C₂, Cr₇C₃ and Ni (Cr) solid solution. Coatings from the manufactured powder were produced by the high velocity oxy-fuel (HVOF) spraying. The abrasive wear tests were carried out according to standard ASTM G65. The wear tests showed that the sprayed coatings from the experimental powder exhibited about five times higher wear rate at abrasive wear conditions than the coatings from the reference commercial powder.

Abstract: Abrasive wear limits the lifetime of key components and wear parts used in various applications. Damage is caused by indentation of harder particles into the wearing materials and subsequent relative motion resulting in ploughing, cutting, and fracture phenomena. The wear mechanisms depend mainly on the applied materials, loading conditions, and abrasives present in the tribosystem, hence material choice is often a difficult task and requires careful evaluation. For this, a variety of laboratory abrasion tests are available of which the scratch test is discussed in this work as the most fundamental abrasive interaction. For further insight into the acting wear mechanisms and microstructural effects, large-scale molecular dynamics simulations were carried out as well as meso-/macroscopic scratch simulations with the mesh-free Material Point Method. The prediction of abrasive wear is of high relevance for industrial applications. Up to now, no general one-to-one match between field application and lab system is known. Here, a simulation-based transfer of experimentally determined wear rates via a lab-2-field approach enables the prediction of wear rates in real applications.

Abstract: This paper dwells upon using the VPr11-40N high-temperature brazing powder as a cladding applied by a laser to restore the height of the airfoil of a turbostarter blade in an NK-12MP turboprop, while also making the edge more wear-resistant. It has been found out that laser cladding generates a highly homogeneous structure with lesser gradient of hardness over the clad area compared to furnace brazing. Abrasive-wear tests have shown that this braze resists abrasive wear better than the blade substrate material (superalloy JS6К heat-resistant intermetallic alloy).

Abstract: The present study is aimed at investigating wear resistance of the heat treated of recycled aluminium type AA6061 for various reinforced methods (heat treatment reinforced by graphite and silica) using pin on disc method. In the study, weight loss value of the recycled chip of AA6061 was observed. Eight specimens were taken for the wear test. The results showed that the wear resistance increased for specimens treated by heat treatment. This increase in wear resistance is value of micro hardness which increased with the increase of the percentage of silica reinforcement. Thus, the weight loss decreased and the volume loss also decreased.

Abstract: Hardfacing weld is a technique which mainly improves and extends the useful life of engineering components. The purpose of this research is to improve welding procedure for one layer and three layers hardfacing of 3.5% Chromium cast steel and to study wear behavior of hardfacing layers. Flux Cored Wire Arc Welding (FCAW) process has been used as a welding process of this research by choosing austenitic stainless steel and martensitic hardfacing wire to weld the buffer and hardfacing layer respectively. Preheating was also used in this study. Abrasive wear test of hardfacing deposit were conducted in accordance with procedure “A” standard of ASTM G65. In addition, microstructures and macrostructure of worn surface deposits were analyzed by using optical microscope. These results showed that there is no crack and defect in the Heat Affected Zone (HAZ) and other regions. The hardness of preheating sample in HAZ regions was lower than the ones without preheating. Therefore, preheating samples should be done before welding. The abrasive wear resistance of three layers hardfacing deposit was better than one layer hardfacing deposit because one layer hardfacing deposit was more diluted from buffer layer than three layers hardfacing deposit. Moreover, weight loss of one hardfacing layer was also higher than three layers.

Abstract: This paper studies the influence of work conditions, difference compression load and counterface roughness, on UHMWPE under abrasive wear test without lubrication according to GOST 426-77. It was found that the formation of deep and wide furrows on worn surface and abrasive intensity increased when the number of grit grade was decreased (average grit size increase). The behavior of abrasive wear can be classified as follows: the first characteristic volume loss quickly increases in the beginning of running time about 5-15 minutes, which is referred to as “run-in” wearing stage; the second characteristic volume loss regularly increases after running time about 15 minutes, which is approaching to “steady-state” wearing stage. In addition, the abrasive wear intensity increase with increasing compression load and/or decreasing number of grit grade (average grit size increase). The results of this research can be applied to abrasive applications in mechanical engineering.

Abstract: This study examined the optimal abrasive wear performance of kenaf-reinforced polymer composite under different sliding conditions. Three different fiber loadings i.e. 43.05, 49.30 and 55.33 vol.% of kenaf fiber was reinforced into a polyester resin using the pultrusion technique. Optimal responses of wear rate and average coefficient of friction (COF) for kenaf fiber-reinforced polyester composites, based on different levels of control factors (fiber loading, applied load, counterface roughness and sliding speed) were determined by the Taguchi Design of experiment (DOE) with L₉ (3⁴) orthogonal array and Analysis of variance (ANOVA) methods. The wear behaviour of kenaf fiber-reinforced composites were investigated using DUCOM pin-on-disc tester with three levels of applied loads (10-30 N), sliding speeds (0.42-1.3 m/s) against different grit sizes of silicon carbide abrasive papers (average grain size~2.2-25.2 μm) under dry sliding condition. The optimization of S/N ratio and degree of significance of the control variables to minimize the wear rate and average COF of kenaf fiber-reinforced polyester composites was carry out. The results showed that the counterface roughness is the most significant factor in affecting the wear rate, followed by applied load, sliding speed, and fiber loading. For average COF, the fiber loading is the most significant factor followed by applied load, sliding speed and counterface roughness.

Abstract: This paper focuses on the influence of hardmetal reinforcement amount, shape and size on the abrasive wear resistance of composite iron self-fluxing alloy (FeCrSiB) based hardfacings produced by the powder metallurgy (PM) technology. First, the size of the reinforcement (1 – 2.5 mm) was fixed, but its shape (angular or spherical) and amount (0 – 50 vol%) were varied. Then the reinforcement shape (angular) and amount (50 vol%) were kept constant, while its size (0.16 – 0.315 mm fine reinforcement and 1 – 2.5 mm coarse reinforcement) and proportion of fine and coarse reinforcement (all fine, all coarse, half fine-half coarse) were varied. ASTM G65 abrasive rubber wheel wear test was applied to find out the wear resistance of the hardfacings; an unreinforced self-luxing alloy (FeCrSiB) hardfacing was the reference material. Volumetric wear rate was calculated according to the weight loss. Worn surfaces were studied under scanning electron microscope. As a result, an optimal composition of the hardmetal containing Fe-based hardfacings based on the reinforcement amount (vol%), shape (irregular or spherical) and size (fine or coarse) is given.

Abstract: The paper relates laboratory experiments in order to obtain a composite material used for brake shoe manufacture. Regarding the testing materials were processed 38 samples. The percentage and composition of materials are: 15-45% novolac, 1,5-10% hexametyltetramin, 0-8% sulfur, 0-15% carbon fiber, 0-20% graphite, 0-25% aluminum, 15-28% brass and 0-40% rubber. The evolution of tribological and temperature parameters were analyzed in the contact zone tribological testing disk - split pin method. The composite material has the role to replace the classic material (cast iron) used in brake shoes composition in order to reduce the noise caused by rolling stock.

Abstract: Tantalum carbide (TaC) gradient composites were fabricated via in-situ fabrication method from the tantalum plate and gray cast iron. The morphology, phase constituents, micro-hardness, and relative abrasion resistance of the composites were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness tester and abrasive wear testing machine. The surface layer, which was ~160μm thick, was dense ceramic layer composed by ~90% submicron TaC particulates. The highest micro-hardness value of the dense ceramic layer was 13.84 GPa. In the sub-layer, the gradient distribution of TaC particulates reflected in the volume fraction decreased from 90% to 0%. While the micro-hardness value decreased from 10.81 GPa to 4.10 GPa. The metallurgical combination of the interface between the composites and matrix was perfect. The wear resistance of TaC reinforced iron matrix surface gradient composites increased significantly.