Research Of SiC-based Ceramic Foam Filiter For Filtering Non-ferrous Metal Melt

With the acceleration of the modern industrial process,the requirements for the mechanical properties and comprehensive quality of castings in important fields such as military industry,communications,aviation,and automobiles have become higher and higher.How to maintain the purity of the molten metal during the melting and pouring process is the key factor that determines the quality of the casting.When the molten metal passes through the current-guiding slot from the melting furnace,ladle or pouring system,impurities will be generated due to oxidation with air or slag dropping from the inner wall of the furnace.The use of a ceramic foam filter in a runner,chute or ladle depending on the process environment,is the simplest and most effective method of filtration.Compared with the working condition and using environment of casting,foam ceramics should be immersed in molten metal solution for at least 5 days in the process of nonferrous metal smelting.Due to its good thermal shock resistance and corrosion resistance,the SiC-based foam ceramic filter can be used in nonferrous metal smelting under more demanding working conditions.However,at present,the SiC-based foam ceramic filter generally has the prominent problems of low compressive strength,and oxidation expansion in the use process,which not only affects the quality of non-ferrous metals,but also the high cost of filters.Based on the advantages of company,this paper systematically studied the factors affecting the formulation of SiC-based ceramic foam filter and discussed the key scientific issues in the preparation processThe main research content is:Silicon carbide was selected as the main system,the multi-component fusible system was innovated,and the optimal composite fluxing system of"Al2O3-SiO2-Suzhou clay-Hebei clay" and its matching relation with principal component were determined.Based on the principle of excellent mechanical properties and small oxidation weight gain rate,the optimal mass ratio of main body system and fluxing system was determined to be 55:45.We could obtain high solid content and low viscosity slurry when the mass ratio of 325 mesh SiC and 1000 mesh SiC was 2:1.At the same time,products with compressive strength of 1.75 MPa,thermal shock resistance of 13 times,and an oxidation resistance of 0.77%can be obtained.Their performance is much higher than the current products,and the production cost is reduced by 6.73%.The influence factors of PAA-Na,PVA,CMC and silica sol composite additives were studied.We could obtain high liquidity slurry with shortened 3h grinding time,and 89%material yield rate when added 0.2wt%PAA-Na.Determined PVA,CMC and silica sol as composity binder system,we could prepared high viscosity and good stability slurry,which could improve the amount of hanging mud of the product's nets and the high temperature strength.SiC-based foam ceramics were prepared by organic foam impregnation method,and systematically studied the factors affecting of preparation process.The researches showed that:The best performance for organic foam pretreatment was immerse in 30%NaOH solution for 2h;In the roll forming process,the optimal ratio of product thickness to roll distance was 5:1 to 6:1,and the optimal number of rolls was 12 to 13 times.The product with the best mechanical properties could be obtained when holding for 2h in a sintering temperature of 1350?.A 10-cubic-meter natural gas kiln with burn-in boards made of SiC board coated with aluminum oxide on the surface and kiln space of 100 mm could solve the problem of burning pollution.In this project,the product with high compressive strength and thermal shock resistance,and low oxidation increase rate could be obtained through the formulation system,additive system and forming process innovation,and solved the problems of oxidation expansion,cracking and collapse,the production cost of raw materials was reduced by 6.73%,the manufacture efficiency was released.Based on the current use of high quality non-ferrous metal smelting filtration,the product can be further applied to precision casting,catalyst carrier,thermal insulation materials and other directions in the future.