Metal Matrix Solid Self-Lubricating Surface Composite Produced By Plasma Melt Injection

Production process, microstructure and properties of Fe/Graphite metal matrix self-lubricating surface composite produced by plasma melt injection (PMI) were investigated.In this thesis, orthotropic technology was applied to design engineering testing which was a three factors three levels orthotropic testing. The three factors included scanning velocity, powder flow and diameter of the nozzle of powder supplier. And particle size (60~80mesh and 20~40 mesh) was regarded as a factor to design monofactorial testing.XRD was applied to analysis substance. Optical microscope and SEM were applied to observe microstructure. EDX was applied for composition analysis. Hardness tester was applied to detect microhardness of layer and wear resistance tester was applied to detect wear resistance of the layer. The result shows that the morphology of specimen can be improved by increasing scanning velocity at constant powder flow, and it also can be improved by increasing powder flow at constant scanning velocity. Scanning velocity and powder flow both have notable influence on microstructure and the influence of powder flow is more powerful. The increasing of scanning velocity contributes to formation of dendrite. The increasing of powder flow contributes to formation of graphite. The nozzle diameter of the powder supplier has no obvious influence on the morphology and microstructure of specimen. Particle size of SiC has distinct influence on the microstructure and more graphite exist in the microstructure produced by PMI 20~40 mesh SiC particles.The constitution of microstructure produced by PMI 60~80 mesh SiC particles is pearlite and nonequlibrium which has a large number of sinkholes. The microhardness of pearlite is HV675 and the microhardness of nonequilibrium is HV798. The wear resistance of the layer is 4.1 times as good as Q235 matrix. Mechanism of wear is adhesion and abrasion. The constitution of microstructure produced by PMI 20~40 mesh SiC particles is a great deal of spherical graphite, nonequlibrium and few of pearlite. Distribution of spherical graphite is homogeneous. Nanometer scare spherical graphite has been found in...