Supersonic flame spraying WC - 10 co4cr coating with low porosity, high bonding strength and excellent wear resistance, etc, have wear-resisting request in aircraft landing gear shaft parts on the size and precision of the repair has been widely used. But, subject to the limit of the process and coating properties, raw coating surface roughness and uniformity of generally cannot meet the requirements of design, must be guaranteed by grinding. In actual production, because of the improper operation or parameters selection is not reasonable to control such links is bad, often leading to parts deformation, thermal stress in coating spalling, crack, or micro cracks and other defects, seriously affect the quality of tungsten carbide coating, restricted the products of normal delivery. By strengthening the materials, equipment and maintenance, manufacturing process and personnel control, put an end to the a type ultra-high strength steel shaft parts coating grinding quality problem happen, and after a long-term practice test, it has reference significance to guide production.

Preparation by supersonic flame spraying process of WC - 10 co4cr coating on the tungsten carbide coating density, porosity < 1%; The combination of coating and substrate in machinery and metallurgy, high bonding strength, can > 70 mpa; Can reach 1100 ~ 1100 hv hardness, high wear resistance can be obtained. The aircraft landing gear shaft parts with wear-resisting requirements, size and precision has been widely used to repair, but subject to the limit of the process and coating properties, original supersonic flame spraying coating surface roughness generally > Ra3.2 mu m, can't meet the design requirements (< Ra0.2 microns).Ultimately, coating thickness and surface roughness must be guaranteed by grinding.

Grinding is the use of high speed rotating diamond grinding wheel,through the coarse grinding and fine grinding to be processed parts surface roughness Ra0.4 ~ Ra0.6 microns, the surface roughness after polishing can achieve Ra0.1 ~ Ra0.2 microns. In actual production, because of the improper operation or parameters selection is not reasonable to control such links is bad, often leading to thermal stress parts deformation, micro cracks appear, the serious influence the quality of coating and restricted the products of normal delivery. In order to ensure the quality of coating grinding, coating process quality control, namely on the material and personnel, equipment and maintenance as well as manufacturing process control, etc.

For grinding tungsten carbide coatingsteel substrates, reasonable control of grinding parameters can effectively prevent the parts surface burns and the thermal stress deformation, put an end to the generation of surface crack defects such as cracks, coating. In the process of grinding, due to the effect of grinding stress, crack in the substrate attaches first, after coating is pulled open, then extend grinding stress perpendicular to the main direction.To reduce the probability of crack, the grinding parameters should be optimized to reduce the stress of grinding, the surface roughness matrix materials at the same time, increase the adhesion strength of the coating and interface.

Posted by: hannahgwendolyn at 09:33 AM | No Comments | Add Comment
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