Papers by Author: Cheng Gao

Abstract: Black ceramic membranes are made on the surface of AZ31B magnesium alloy to further study the micro-arc oxidation coloring ceramic membranes with more colors.In the system of sodium silicate - copper sulfate, black ceramic membrane with good compactness and uniform color can be made while the concentration of sodium silicate is 20g/L and the concentration of copper sulfate is 1.0g/L. Experimental results show that the chroma of the membrane varies from light color system to deep color system with the increasing content of copper aluminum compounds.

Abstract: Copper and Indium alloys elements were metallized into 304 Stainless Steel surface by Double Glow Plasma Surface Alloying Technology (Double Glow Technology for short). Microstructure and Resistance property of diffusion layer analyzer was analysed by metallographic microscope, scanning electron microscopy, energy spectrum, friction and wear testing machine of high speed reciprocating. The results show that process parameters of the permeability copper and indium has an obvious effect for the organization structure and performance of diffusion layer. The friction coefficient of alloying layer has a significant decrease compared with the substrate. The wear-resisting performance has an effective change.

Abstract: 2A12 alloy by MAO on main salts electrolyte system of phosphate sodium is investigated. By contrast test, the influences of arc starting voltage, the thickness of the ceramic layer , growth rate, and wear resistance with different K₂Cr₂O₇ concentration are analyzed. If K₂Cr₂O₇ concentration is 2.5g/L , the arc starting voltage reached the lowest, the surface topography is the best, the wear resistance is the well.

Abstract: In this paper, the author uses double glow plasma surface metallurgy technology, prepares antibacterial stainless steel with copper-cerium case on its surface, does some research on how work-piece space affects Copper-cerium case thickness and component in the case. According to experiment, we find in the range of 10 mm to 25 mm, copper-cerium case depth firstly increase and then decrease with the distance expands; copper-cerium component first rises and then falls with the work-piece space .When the distance is 15mm, hollow cathode effect forms between two plates, we can obtain ideal copper-cerium alley case.

Abstract: The Cu-Ce infiltration layer was formed on 304 Stainless Steel surface by double glow plasma surface metallurgy technology. The effects of heat insulation temperature and heat insulation time on surface alloying concentration, surface hardness and infiltration layer depth were analyzed by comparative test. The results showed: In the experimental range, the contents of Cu and Ce, surface hardness, diffusion layer depth increase with the temperature and time increasing; the deposition layer depth increases with time increasing and decreases with temperature increasing in a certain range.

Abstract: The Cu-Ce infiltration layer was formed on 304 Stainless Steel surface by double glow plasma surface metallurgy technology. The effects of source voltage and cathode voltage on surface alloying concentration, surface hardness and infiltration layer depth were analyzed by comparative test. The results showed: In the experimental range, the contents of Cu and Ce, surface hardness, deposition layer depth increase with the source voltage increasing, which is contrary to the cathode voltage; the diffusion layer depth increases with either voltage increasing in a certain range.

Abstract: In this paper, ceramic coatings were produced on LY12 aluminum alloy by the micro-arc oxidation (MAO) technique in an alkali sodium silicate electrolyte consisting of different KF concentrations(0~15g/l). The influence of KF concentration on making energy consumption and thickness of the MAO coatings was studied. Results revealed that increasing KF concentration caused an increase in the thickness and roughness of coatings and a decrease in the average energy during the MAO process. In response to the increase in KF concentration, the little content of F- in the coatings were increased simultaneously. However, the phase structure and composition of the coatings hardly varied with different KF concentrations. Moreover, it was observed that the coatings produced in electrolytic solution with 10g/L concentration of KF obtained an excellent thickness and making energy, but the coatings were ablated locally with the KF concentration of higher than 10g/L for more than 60 minutes.

Abstract: Based on the plasma nitriding technique, the double glow plasma surface metallurgy (DG-PSM) technology was developed. This technology is also known as the Xu-Tec Process which utilizes solid metallic elements such as Ni, Cr, Mo, W, Ti, Al, Nb, Zr and their combinations to accomplish plasma surface alloying. Mo-Cr strengthened coating was prepared on the surface of low carbon steel Q235 by this technology. This coating is used to high wear resistant cold die LD steel. By experiment of the three different prescriptions in source cathode, the effect of source cathode composition on the coating has been studied. The technological parameters were as follows: The ratio of Mo and Cr were 2:1, 4:1 and 6:1. The work-piece material is Q235 low carbon steel. Holding time is 4h. Holding temperature 1050°C.Source cathode structure was threadiness. The consequences of composition analysis and microstructure observation results show that, most approaches the purpose of this research is the ratio of Mo and Cr is 6:1, and the alloyed layer has stronger adhesion with substrate.

Abstract: Antibacterial properties of compound coatings by Micro-arc oxidation and electroless silver plating were reached. Effects of main salt, reducing agent, complexing agent and solution pH on plating rate and solution stability were discussed. The surface morphology and antibacterial properties of compound coatings were analyzed. Bonding strength between compound coatings was tested by tensile peeling method. The results show that compound coatings have good antibacterial effects, the average bonding strength of compound coatings is higher than 22.6 MPa, and compound coatings are firmly bonded.