| This thesis has designed tungsten carbide particle reinforced composite on the surface of parts aimed at severely erosive and abrasive service condition. The composite results of series matrices (low chromium cast iron cast steel ductile cast-iron grey cast iron ) have been investigated respectively, both Composite and casting techniques have been improved and optimized and applied to fabricate slurry pump. The composite microstructure and forming mechanism have been also analyzed. At the same time, it erosive resistance has been tested compared with high chromium cast iron. The results showed that, particle reinforced composite on the complicated surface could be fabricated by means of sodium silicate sand mold combinated with vacuum infiltrating process. Though the matrix was 10mm, composite layers reached 3mni to 7mm in thickness with high strength interface and less casting ?defect. microstructure of composites could be fallen into three parts. They were matrix zone transition zone and composite zone. tungsten carbide particles distributed uniformly, retaining approximately quondam granular form in composite layers which were make up of high chromium cast iron mainly. With the technique of mould compaction, components of 4slurry pump perfectly achieved portion composite on the surface of been abrased. low chromium cast iron and grey cast iron matrix had good composite layer while Cast steel and ductile cast-iron matrix had bad, especially when pouring temperature was in the range of 1550 centigrade to 1600 centigrade. But low chromium cast iron didn meet the case of manufacture workpieces with big curvedsurface closed because of great difference batween it's thermalcharacteristics and comPosite layer's. Erosive resistance ofparticle reinforced metal matrx comPosite, in Which the matrix islow chromium cast iron and tUngStCn carbide partcle size is0.315mm to 0.400nun with 27% in volume fraction, is 2.7 timesas that of high chromum cast iron (Cr15Mo2 )... |
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