Research On Temperature Field Numerical Simulation And Performance Of Laser Re-melted AT-13 Coating Oriented By Plasma Spraying On 45 Steel

The characters of special material and its surface, especially the characters of machines'parts, are demanded higher and higher than ever with the development of science and technology and the need of industry modernization and arm equipment. Scientists of every country have done plentiful experiments and investigations of theory about how to improve the characters of material and its surface, and they have positively accelerated the development of surface engineer.Plasma spraying is an important technology of surface treatment. Coating is able to fortify and restore the surface of materials. What is more, it can also assign specific performance to the surface of materials. Laser re-melting is a new technology of materials elaboration and surface reshaping, which can produce high performance surface on 45 steels with low cost, so considerable high-grade alloy is substituted. We carry out laser re-melting on plasma spraying by combining the two technical features together. Re-melting layer which is of uniformity, high density, and strong connectivity with basal body is procured by optimized re-melting technology parameters. The combination style of coating and basal body has changed from physico-Combination to metallurgy Combination, so the resistance to wear, binding strength and mechanical function of materials are improved greatly. Therefore, it is significant to investigate Plasma spraying technology and laser re-melting and to optimum design parameter.Firstly, simulation method was used in studying the regular of transient temperature field of 3D moving jet Plasma sprayed AT-13 coating laser re-melting in the paper. Then the laser parameters were optimized, and finally laser re-melting sample performance was tested. Works had been done as follows:1. Technology of surface engineer and coating theory The technology of surface engineer and the coating theory must be researched by reading a lot of papers and materials before carrying through plasma spraying and dealing with the plasma-spraying coat by using laser re-melting, in order to design the logical plasma-spraying coat reasonably and make the plasma-spraying coat and the re-melting coat reaching to the best effect. All of these have offer theory to the research of the plasma-spraying coat and the laser re-melted coat.2. Distribution regularity of temperature field is studied according to the heat transfer theory and numerical simulation method. Considering the thermo-physical parameters, heat convection and phase-change latent heat changing with temperature change, computing model of temperature field of continuously moving 3D transient laser re-melting plasma spraying AT-13 coating is build up with ANSYS Finite Element Method software. Coating and basal body surface layer are required to reach melting point, which make the combination style changing from mechanical Combination to metallurgy Combination. Discuss the influence of laser parameter on depth and width of fusing bath: indicate temperature apogee stepping up, fusing bath width waxing and fusing bath depth deepening with the increasing of power under the condition that scanner speed and the radius of laser light spot are invariable; indicate temperature apogee stepping down, fusing bath width shrinking and fusing bath depth becoming shallow with the increasing of scanner speed under the condition that laser power and the radius of laser light spot are invariable; indicate temperature apogee stepping down, melting bath width waxing and melting bath depth becoming shallow with the increasing of the radius of laser light spot under the condition that laser power and the scanner speed are invariable. A temperature field model which could guide the experiment is established after amending the analogue by comparing and analyzing the calculated conclusions and experimental results repeatedlarea cribrosa papillae renalis.3. Shapes (depth and width) of hard zone and fused bath , distribution regularity of temperature field in laser re-melting process of plasma spray painting AT-13 coating and influences of laser power, scanning speed and facular radius to the field distribution are discussed in the paper. In order to get the hard zone which is thick and has good-quality superficial coat, surface temperature should not be high. While, the higher the temperature of binding place between basal body surface and coating, the deeper of harden layer depth. Laser processing parameters, such as laser power, scanning speed and facular radius, are optimized with the model established, obtaining the ideal hard zone.4. Laser re-melting test piece have undergone hardness measure, binding strength calculation, wearing performance test. The structure and phase of AT-13 plasma spray painting coating which has undergone laser re-melting has changed which discovered by SEM and XRD. The structure is of high density and pores vanish. Particles become smaller. The essential component of coating isα-Al₂O₃ and there is a small quantity of TiO2 in coating, which generate TiAl₂O₅. The highest value of the micro-hardness of re-melting layer ( HV0.2 ) has reached to 1710, binding intensity between re-melting coating and basal body has exceeded 68.8Mpa, the abradability has greatly improved compared with AT-13 plasma spray painting coating and 45 steel. The performance index of coating has achieved original height. Coating has conspicuously improved on hardness, abradability and binding intensity with basal body.