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Composite materials produced by powder metallurgy provide a solution in many engineering applications where materials with high abrasion and erosion resistance are required. The actual wear behaviour of the material is associated with many external factors (particle size, velocity, angularity, etc.) and intrinsic material properties (hardness, toughness, Young modulus, etc.). Hardness and toughness properties of such tribomaterials are highly dependent from the content of reinforcing phase, its size and from the mechanical properties of the constituent phases. In this study an attempt is made to model the erosion wear behaviour of composite materials, to calculate the wear rate and to correlate erosion rates with experimental results and material parameters. Powder composites cermets and metal-matrix composite materials reinforced with different content of hard phase were used as examples in this research. Wear mechanisms of materials were investigated. Following from the main mechanisms of erosion wear the models of plastic deformation and brittle fracture are developed for prediction of erosion of powder composite materials. It was demonstrated, that the erosion rate of hardmetal-type materials can be predicted using the results obtained by microindentation methods. The use of hardness distribution parameters is justified with materials with low binder content. 相似文献
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Conclusions A laboratory plant for the preparation of H2 + CO protective atmospheres from propane-butane gas or dissociated ammonia at a rate of up to 0.4 m3/h has been constructed and tested.Translated from Poroshkovaya Metallurgiya, No. 4 (148), pp. 94–96, April, 1975. 相似文献
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Recycled hard metal-base wear-resistant composite coatings 总被引:1,自引:0,他引:1
The abrasion-erosion wear resistance of composite coatings from self-fluxing Ni-base alloy and WC-Co hard metal powders is
evaluated. The resistance of thermal sprayed and melted NiCrSiB-(WC-Co) coatings was found to be markedly higher than that
of NiCrSiB and slightly higher than that of comparative welded coatings. Microstructural and surface analyses were used to
describe the coatings and the wear damage. Based on the principles of creating wear-resistant coatings and on experimental
studies of wear resistance, high wear-resistant, composite NiCrSiB-(WC-Co) coatings were fabricated. These coatings exhibited
300% higher wear resistance than 0.45% C steel. 相似文献
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V. Podgursky T. Hantschel A. Bogatov E. Kimmari M. Antonov M. Viljus V. Mikli M. Tsigkourakos W. Vandervorst J. G. Buijnsters A. T. Raadik P. Kulu 《Tribology Letters》2014,55(3):493-501
The formation of nanoscopic ripple patterns on top of material surfaces has been reported for different materials and processes, such as sliding against polymers, high-force scanning in atomic force microscopy (AFM), and surface treatment by ion beam sputtering. In this work, we show that such periodic ripples can also be obtained in prolonged reciprocating sliding against nanocrystalline diamond (NCD) films. NCD films with a thickness of 0.8 µm were grown on top of silicon wafer substrates by hot-filament chemical vapor deposition using a mixture of methane and hydrogen. The chemical structure, surface morphology, and surface wear were characterized by Raman spectroscopy, scanning electron microscopy (SEM), and AFM. The tribological properties of the NCD films were evaluated by reciprocating sliding tests against Al2O3, Si3N4, and ZrO2 counter balls. Independent of the counter body material, clear ripple patterns with typical heights of about 30 nm induced during the sliding test are observed by means of AFM and SEM on the NCD wear scar surfaces. Although the underlying mechanisms of ripple formation are not yet fully understood, these surface corrugations could be attributed to the different wear phenomena, including a stress-induced micro-fracture and plastic deformation, a surface smoothening, and a surface rehybridization from diamond bonding to an sp 2 configuration. The similarity between ripples observed in the present study and ripples reported after repeated AFM tip scanning indicates that ripple formation is a rather universal phenomenon occurring in moving tribological contacts of different materials. 相似文献
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Selection criteria for wear resistant powder coatings under extreme erosive wear conditions 总被引:1,自引:0,他引:1
Wear-resistant thermal spray coatings for sliding wear are hard but brittle (such as carbide and oxide based coatings), which
makes them useless under impact loading conditions and sensitive to fatigue. Under extreme conditions of erosive wear (impact
loading, high hardness of abrasives, and high velocity of abradant particles), composite coatings ensure optimal properties
of hardness and toughness. The article describes tungsten carbide-cobalt (WC-Co) systems and self-fluxing alloys, containing
tungsten carbide based hardmetal particles [NiCrSiB-(WC-Co)] deposited by the detonation gun, continuous detonation spraying,
and spray fusion processes. Different powder compositions and processes were studied, and the effect of the coating structure
and wear parameters on the wear resistance of coatings are evaluated. The dependence of the wear resistance of sprayed and
fused coatings on their hardness is discussed, and hardness criteria for coating selection are proposed. The so-called “double
cemented” structure of WC-Co based hardmetal or metal matrix composite coatings, as compared with a simple cobalt matrix containing
particles of WC, was found optimal. Structural criteria for coating selection are provided. To assist the end user in selecting
an optimal deposition method and materials, coating selection diagrams of wear resistance versus hardness are given. This
paper also discusses the cost-effectiveness of coatings in the application areas that are more sensitive to cost, and composite
coatings based on recycled materials are offered. 相似文献