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Fe-based composite coatings reinforced with TiC particles were prepared by laser surface engineering from precursor of ferrotitanium and graphite. Microstructure of the composite coatings was comprised of dendritic TiC dispersed in a ferrite matrix. In situ dendritic TiC was formed by mechanism of precipitating from the liquid Fe-Ti-C alloy system. Composite coatings showed a substantial increase in microhardness in comparison to that of the substrate. Dry sliding wear tests performed at room temperature revealed that the in situ composite coating possessed a considerably reduced wear volume loss owing to the presence of in situ synthesized TiC. A relatively smooth surface was observed for in situ TiC/Fe composite coating due to its high resistance to ploughing and adhesion, which is caused by the uniformly dispersed TiC reinforcement with high volume fraction. [ABSTRACT FROM AUTHOR]

In situ titanium carbide reinforced iron-based composite coating was deposited on mild carbon steel using laser surface engineering (LSE) with ferrotitanium and graphite as precursor. The microstructure and phase constituents of the deposited coating were characterized. Formation mechanism of titanium carbide crystal in the composite coating was elucidated by correlating the morphology of titanium carbide and the thermal cycle experienced by the precursor during the laser treatment. It was demonstrated that titanium carbide was formed in situ as a result of the metallurgical reaction between ferrotitanium and graphite following a liquid-precipitation route. Different morphologies of titanium carbide crystal (dendrite and fishbone) correspond to the primary and eutectic titanium carbide respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this study, in situ multiple carbides reinforced Fe-based surface composite coatings were fabricated successfully by laser cladding a precursor mixture of graphite, ferrotitanium (Fe–Ti) and ferromolybdenum (Fe–Mo) powders. The results showed that (Ti, Mo)C particles with flower-like and cuboidal shapes were in situ formed during the solidification and most shapes of (Ti, Mo)C particles were diversiform according to different contents of Fe–Mo powder in the Fe–Ti–Mo–C system. The growth morphology of the reinforcing (Ti, Mo)C carbide has typically faceted features, indicating that the lateral growth mechanism is still predominant growth mode under rapid solidification conditions. Increasing the amount of Fe–Mo in the reactants led to a decrease of carbide size and an increase of volume fraction of carbides. The coatings had good cracking resistance when the amounts of Fe–Mo were controlled within a range of 15wt%. [Copyright &y& Elsevier]

Abstract: In this study, different hardfacing layers were produced by shield manual arc welding (SMAW) process in which a bare electrode of H08A was coated with fluxes, to which different measures of ferrotitanium (Fe–Ti), ferrovanadium (Fe–V), ferromolybdenum (Fe–Mo) and graphite had been added. The influence of added alloy elements on the microstructure and wear properties of the Fe-based hardfacing layers was investigated. The results showed that complex carbides of TiC–VC–Mo2C were synthesized via metallurgic reaction during welding. Carbides are uniformly dispersed in the matrix. The addition of graphite and ferromolybdenum can enhance macro-hardness and wear resistance of the hardfacing layer significantly, but increase the crack sensitivity of the hardfacing layer. With the increasing of the additions of Fe–Ti and Fe–V, the macro-hardness and wear resistance of the hardfacing layers increased. A good resistance to cracking and wear resistance of the hardfacing layer could be obtained, when the amounts of graphite, Fe–Ti, Fe–V and Fe–Mo were controlled within a range of 8–10%, 12–15%, 10–12% and 2–4%, respectively. The wear resistance of the deposited layer surfaced by Fe–Ti–V–Mo–C hardfacing alloy possesses a higher wear resistance and less friction coefficient than that of the deposited layer surfaced by EDRCrMoWV-A3-15 hardfacing alloy. [Copyright &y& Elsevier]

Abstract: The microstructure and wear behavior of WC–8TiC–3TaC–8Co cemented carbide and CuZnNi alloy composite strengthening materials have been investigated by means of scanning electron microscopy (SEM), electron dispersion X-ray analysis (EDAX) and wear test. Effect of applied load and sliding distance on the wear behavior of the strengthening materials are also studied in this paper. The results show that the cemented carbide particles are surrounded by the α+β phases in the hardfacing layers. There exists an inter-diffusion zone at the interface of the cemented carbides and Cu-based matrix due to the mutual diffusion of elements. The wear volume of both the WC–8TiC–3TaC–8Co/CuZnNi and WC–8Co/CuZnNi composite strengthening layers increased with the increasing of applied load. The WC–8TiC–3TaC–8Co/CuZnNi hardfacing layers exhibited lower wear volume loss than that of WC–8Co/CuZnNi. According to the results of engineering application, the working efficiency and employing life of the milling shoes, which were strengthened by WC–8TiC–3TaC–8Co/CuZnNi composite materials, is by approximately two to three times the milling tools strengthened by WC–8Co/CuZnNi. [Copyright &y& Elsevier]

Abstract: The microstructure and wear behavior of WC–TiC–Co/CuZnNi composite surface coating has been investigated by means of scanning electron microscope (SEM), electron dispersion X-ray analysis (EDXA) and wear test. The oxidation behavior of WC–8TiC–8Co and WC–8Co hard metal in the temperature range between 600 and 1000°C was also researched. The oxidation mass gain of WC–8TiC–8Co hard metal is less than the WC–8Co hard metal. The particle of hard metal is surrounded by the α-Cu+β-Zn phase in the surface coating. The size of hard metal is almost unchanged from its original one. There exists an inter-diffusion zone at the interface of the hard metals and Cu-based matrix. The wear volume of both the WC–8TiC–8Co/CuZnNi and WC–8Co/CuZnNi composite surface coatings increased with the increasing of applied load. However, the composite surface coating of WC–8TiC–Co/CuZnNi exhibited lower wear volume than that of WC–8Co/CuZnNi composite surface coating. According to the results of engineering application, the working efficiency and employing life of milling tools, which were surfaced WC–8TiC–8Co/CuZnNi surface coating, is by approximately 2–3 times the milling tools surfaced WC–8Co/CuZnNi surface coating. [Copyright &y& Elsevier]

TiC particle reinforced Ni-based alloy composite coatings were clad to AISI 4140 chromium molybdenum alloy steel substrate using a laser. The microstructure and tribological behavior of coatings were studied experimentally by means of scanning electron microscopy, transmission electron microscopy and wear tests. Partial solution of TiC particles occurs in the laser melting pool during the heating stage. Twins and dislocations were observed at the interface of TiC particles and the matrix. The wear resistance was found to correlate with the load and amount of the TiC particles present in the clad layer. By adding La2O3, the hardness of clad coatings was significantly increased, and the wear resistance of clad coatings was enhanced. [Copyright &y& Elsevier]

Abstract: In situ synthesized TiB2 reinforced Fe based coating was fabricated by laser cladding on steel substrate using cheaper Fe–Ti alloy, Fe–B alloy and Fe as the precursor powders. The phase composition and microstructure of the clad layer were investigated by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Results showed that uniformly distributed TiB2 particles with the hexagonal shape could be synthesized by the in situ reaction. The hardness and wear properties of the clad layer were greatly improved due to the presence of TiB2 particles in comparison with the substrate. [Copyright &y& Elsevier]