Papers by Keyword: Composite Powders

Abstract: The paper presents the results of development and study of a composite powder of Ti-TiB₂ system. Comprehensive studies of composite coatings formed by microplasma spraying of the developed powders are carried out. It is determined that the developed composite materials are promising for use in elements and friction units of wind power plants and shipbuilding engineering objects.

Abstract: The CNTs/Al2009 composite powders were prepared by cryogenic milling. The CNTs were uniformly dispersed on the surface of Al2009 powders. And then the CNTs/2009Al composites were fabricated by hot extrusion/hot isostatic pressing method. The effects of CNTs content and cryogenic milling process on the dispersion of CNTs in Al2009 matrix, the microstructure of powders and the properties of composites were studied by Scanning electron microscopy, Raman spectroscopy and tensile strength testing at room temperature. The results showed that the dispersion of CNTs was improved with the extension of ball milling time (1h~4h), but the damage degree of CNTs was intensified. In comparison, CNTs had the highest damage rate at the beginning of ball milling. As the milling time increased, the mechanical properties began to increase slightly and then decreased. When the ball milling time was 2h, the mechanical properties reached the highest. Cryogenic milling could achieve good dispersion in the Al2009 matrix for mixed powders with low CNTs content. When the CNTs content increased to 1.0%, a small amount of agglomeration appeared, but for composites, the strengthening effect of CNTs was more dominant. When CNTs were further added, the dispersion was remarkably lowered and the performance was deteriorated. CNTs (1.0wt.%)/Al2009 composites had excellent mechanical properties. The tensile strength reached 560MPa, which was 25% higher than Al2009.

Abstract: The results of experimental studies show that the use of composite powders (WC-Co) in combination with the modification by the additives of ceramic nanoparticles allows controlling the parameters of the microstructure and increasing the strength of the binder and the level of physical and mechanical properties of the hard metal in general. The coating of carbide particles with a layer of a binder is an effective starting method that allows to obtain a bulk compound that preserves the unique properties of the initial nanopowders and ensures a uniform distribution of the phases (WC, Co, Al₂O₃). Such multiphase fragmentary nanostructured composite is characterized by additional heterogeneity, determined by the differences in size and elastic properties of the phases. By combining the sizes and properties of the phase components in such heterogeneous composite, it is possible to increase the fracture energy (i.e. Palmqvist fracture toughness) up to 20 - 22 MPa∙m^1/2 as a result of inhibition on inclusions of nanoparticles the stress relaxation and change in the trajectory of the intergranular crack. Based on the proposed stereological models and experimentally established relationships between composition and microstructure parameters, the required volume concentrations of nanoparticles’ additives and composite powders (WC-Co) were determined.

Abstract: The development of additive manufacturing (SLS/SLM, EBM, DMD) suggests the increase of the range expansion of materials used. One of the most promising directions is products manufacturing from composite materials. The technology of composite micro-powders production on the basis of heat-resistant nickel alloy EP648 and TiC is proposed. The aim of this research is to develop a method of producing composite micropowders for additive technology application. This method is based on modification of the metal micropowders surface by the second phase in a planetary mixer (mechanochemical synthesis).The obtained composite micropowders are compared with powders which are recommended for selective laser melting usage (produced by MTT Technology). The equipment used in the research: planetary mixer, scanning electron microscopy (SEM), optical granulomorphometer Occio 500nano.

Abstract: Zirconium diboride (ZrB₂) ceramics with high melting point, high hardness, good electrical and thermal conductivity, good neutron control and other characteristics, can be widely used in high-temperature structural ceramics, composite materials, electrode materials. In order to improve ZrB₂ difficult densification and high-temperature oxidation, the properties of coated Al (OH)₃-Y(OH)₃/ZrB₂ composite powders prepared by co-precipitation method were investigated in this paper, The conclusions are shown that the effect of coated composite powders is getting worse with the accelerated titration rates. the coating effect will be worse with the increasing reaction time. When the concentration of mixed solution is lower, the coated effect is better. When the synthesis condition is that the titration rate of 10ml/min, and the reaction time was 1h, mixed solution ion concentration of Y³⁺=0.119mol/L and Al³⁺=0.231mol/L, the coated effect of composite powders is better.

Abstract: The phase composition, microstructure and morphology of composite powders «TiC-HSS steel binder» obtained by the SHS method in layerwise combustion mode have been studied. Titanium powder, carbon (carbon black) in a ratio corresponding to equiatomic titanium carbide and high speed steel as a thermally inert binder was used as a reaction mixture. It was found that the mass transfer of reaction mixture components between the carbide and metal binder was taking place during synthesis, as a result of which the final phase and elemental composition of the synthesis products was formed. It is shown that the volume content of thermally inert binder significantly affects the dispersion of the formed carbide phase.

Abstract: The technology of composite micropowders’ obtaining that allows the production of a wide range of composite powders suitable for use in additive technologies is proposed. The technology includes modification of the metal powder surface with the mechanochemical treatment. The production modes for the AlSi12-Al₂O₃ composite powder are determined.

Abstract: Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, prepared by calcination of alumina - aluminum metal-ceramic composite material powder, and its characterization as a basis to provide raw materials for preparing high performance metal ceramic material. According to the research, with the calcination temperature is increased, the rate of change gradually increase the weight of aluminum. Calcined at a temperature of 600¡æ, the oxidation of aluminum surface the best. With the firing time increases, the rate of change in the weight of aluminum powder showed an increasing trend. When 8h, oxidation of aluminum surface better. Through this experiment, process optimization can be found in the calcination temperature was 600¡æ, calcination time is 8h, the best coating effect aluminum surface, coating evenly, clean interface, the reaction layer thickness of about 700nm, the prepared package type composite powders the best results.

Abstract: The paper presents the result of studies of composite powders produced by self-propagating high temperature synthesis (SHS) in the reaction mixtures of titanium, carbon and high chrome cast iron, and electron-beam coatings based on them. It was found that the morphology and dispersion of titanium carbide particles in the SHS-product were determined by cast iron powder content in the reaction mixtures. The effect of content of the SHS powders on the characteristics of electron-beam coatings, including abrasive wear resistance of facing coatings was shown.

Abstract: A structure of Ti-TiC coatings with different content of titanium binder, overlaid of composite powders, which were obtained by self-propagating high-temperature synthesis, was investigated. The structure was studied by X-ray analysis and metallography. A size of the carbide particles in coatings, hardness of coatings and rate of wear were measured.