This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of lo...This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.展开更多
ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium ...ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium and carbon steel are presented. A metallurgical bonding between the coating and substrate is obtained. The Ti element was found to distribute in WC92-Co8 at the metal pool, as well as the interface by diffusion. Some new phases were produced in the coating layer due to the chemical reaction during the ESD process. Experimental observation and thermodynamic analysis were utilized to study the mechanism of ESD.展开更多
Using electrospark alloying machine, a series of experiments were carried out to investigate the effect of electrospark surface strengthening process on the microstructure and the properties of the coatings with ultra...Using electrospark alloying machine, a series of experiments were carried out to investigate the effect of electrospark surface strengthening process on the microstructure and the properties of the coatings with ultrafine cemented carbide as electrode material and white cast iron as substrate material. The results indicated that the optimum process parameters to be used reached a satisfying coating surface. Wear test results showed the coatings had a high wear-resistance.展开更多
In the electrospark deposition (ESD) of WC-Co materials on low carbon steel, tungsten carbide (WC) decarburization is observed. The use of an inert atmosphere (argon) does not eliminate the problem of tungsten carbide...In the electrospark deposition (ESD) of WC-Co materials on low carbon steel, tungsten carbide (WC) decarburization is observed. The use of an inert atmosphere (argon) does not eliminate the problem of tungsten carbide decarburization during electrospark processing. The effect of the carbon concentration of electrode materials on the phase composition and mechanical properties of WC (10 wt% of Co) ESD coatings has been investigated in this work. The introduction of additional carbon (graphite) in the electrode material on the basis of the WC-10%Co leads to an increased amount of WC in the obtained coatings and thus improves their wear resistance.展开更多
The structure and properties of coatings based on WC-Co alloys containing additives of 1% - 5% aluminium oxide and 2.5% - 4.5% carbon were investigated. The coatings had a nanocrystalline structure. Depending on the d...The structure and properties of coatings based on WC-Co alloys containing additives of 1% - 5% aluminium oxide and 2.5% - 4.5% carbon were investigated. The coatings had a nanocrystalline structure. Depending on the duration and frequency of the discharge pulses, the ratio between WC and W2C in the coatings was different. The additives in the hard alloy allowed us increase the microhardness and wear resistance of the coatings by a factor of 2 - 3 in comparison to coatings created using a conventional WC-10%Co alloy.展开更多
Taking Ni45 bar as electrode,a strengthened layer of thickness up to 50μm was built up on BT20 titanium alloy matrix by means of electrospark deposition.Results of phase analysis by using of X-ray diffraction confirm...Taking Ni45 bar as electrode,a strengthened layer of thickness up to 50μm was built up on BT20 titanium alloy matrix by means of electrospark deposition.Results of phase analysis by using of X-ray diffraction confirmed that the deposition layer was composed mostly of three phases,NiTi,NiTi2 and Ti.The surface microhardness of the deposition layer was up to 910 HV0.05,about 2.7 times as high as that of the matrix.The hardness at the cross-section of the entire deposition layer showed a gradient distribution.The effects of capacitance and deposition time on thickness of deposition layer were also studied,and results showed that with relatively low capacity and short deposition time the deposition layer without cracks can be obtained.展开更多
MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior ...MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior of the composite coatings were studied. The results showed that the composite coatings were composed of superfine 9' columnar dendrite and large TaC particles dispersedly distributed. The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.展开更多
Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique (ESD). Forming properties, thickness, microhardness and wear resistance of the coatings were investigated. The ch...Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique (ESD). Forming properties, thickness, microhardness and wear resistance of the coatings were investigated. The chemical composition and cross- section morphology were analyzed through energy dispersive spectrum (EDS) and metalloscope. The results show that the technological parameter window of Ni398 is larger than that of Ni818 electrode. However, other properties of the Ni818 coating, such as thickness and microhardness, were better than those of the Ni398 coating. Especially the wornout volume of Ni818 coating is only 1/6 of that for 1045 steel and 1/3 for Ni398 coating. Chemical composition analysis indicated that the addition of Mo promoted grain refinement of nickel alloy. Metallographic analysis shows that the molten droplets of Ni398 coatings have an average structure thickness of 20-40 #m while the microstructure of Ni818 coatings is flat with width of 5-20 #m.展开更多
文摘This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.
文摘ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and interfacial characteristics of the WC92-Co8 coated on titanium and carbon steel are presented. A metallurgical bonding between the coating and substrate is obtained. The Ti element was found to distribute in WC92-Co8 at the metal pool, as well as the interface by diffusion. Some new phases were produced in the coating layer due to the chemical reaction during the ESD process. Experimental observation and thermodynamic analysis were utilized to study the mechanism of ESD.
文摘Using electrospark alloying machine, a series of experiments were carried out to investigate the effect of electrospark surface strengthening process on the microstructure and the properties of the coatings with ultrafine cemented carbide as electrode material and white cast iron as substrate material. The results indicated that the optimum process parameters to be used reached a satisfying coating surface. Wear test results showed the coatings had a high wear-resistance.
文摘In the electrospark deposition (ESD) of WC-Co materials on low carbon steel, tungsten carbide (WC) decarburization is observed. The use of an inert atmosphere (argon) does not eliminate the problem of tungsten carbide decarburization during electrospark processing. The effect of the carbon concentration of electrode materials on the phase composition and mechanical properties of WC (10 wt% of Co) ESD coatings has been investigated in this work. The introduction of additional carbon (graphite) in the electrode material on the basis of the WC-10%Co leads to an increased amount of WC in the obtained coatings and thus improves their wear resistance.
文摘The structure and properties of coatings based on WC-Co alloys containing additives of 1% - 5% aluminium oxide and 2.5% - 4.5% carbon were investigated. The coatings had a nanocrystalline structure. Depending on the duration and frequency of the discharge pulses, the ratio between WC and W2C in the coatings was different. The additives in the hard alloy allowed us increase the microhardness and wear resistance of the coatings by a factor of 2 - 3 in comparison to coatings created using a conventional WC-10%Co alloy.
文摘Taking Ni45 bar as electrode,a strengthened layer of thickness up to 50μm was built up on BT20 titanium alloy matrix by means of electrospark deposition.Results of phase analysis by using of X-ray diffraction confirmed that the deposition layer was composed mostly of three phases,NiTi,NiTi2 and Ti.The surface microhardness of the deposition layer was up to 910 HV0.05,about 2.7 times as high as that of the matrix.The hardness at the cross-section of the entire deposition layer showed a gradient distribution.The effects of capacitance and deposition time on thickness of deposition layer were also studied,and results showed that with relatively low capacity and short deposition time the deposition layer without cracks can be obtained.
基金supported by the National Natural Science Foundation of China(No.50901081)
文摘MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior of the composite coatings were studied. The results showed that the composite coatings were composed of superfine 9' columnar dendrite and large TaC particles dispersedly distributed. The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents.
基金supported by the National Natural Science Foundation of China(No.50801066)
文摘Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique (ESD). Forming properties, thickness, microhardness and wear resistance of the coatings were investigated. The chemical composition and cross- section morphology were analyzed through energy dispersive spectrum (EDS) and metalloscope. The results show that the technological parameter window of Ni398 is larger than that of Ni818 electrode. However, other properties of the Ni818 coating, such as thickness and microhardness, were better than those of the Ni398 coating. Especially the wornout volume of Ni818 coating is only 1/6 of that for 1045 steel and 1/3 for Ni398 coating. Chemical composition analysis indicated that the addition of Mo promoted grain refinement of nickel alloy. Metallographic analysis shows that the molten droplets of Ni398 coatings have an average structure thickness of 20-40 #m while the microstructure of Ni818 coatings is flat with width of 5-20 #m.