Cast Iron Surface Alloy-the EPC Infiltration Processing And The Study On The Microstructure And Performance Of Alloy Layer

Cast iron is one of the most important materials in the field of industry, parts made by cast iron move by one another brings friction and abrasion. Abrasion is one of the top three reasons for part disablement,it is the main reason for ullage of energy and material .According to Stat., because of friction and abrasion, the loss of economy reach to 4000 hundred million each year .so the solution for abrasion attracted people .In order to improve abrasion performance, we appends alloy elements into part, it is works .but abrasion always happens on surface and the alloy elements which can improve abrasion performance are always expensive, so changing the whole performance of parts is a avoidable waste .the most effective method is surface alloy .Both infiltrate metal and cast infiltrating are methods of surface alloy. infiltrate metal have many disadvantage such as long management time,high treating temperature,thin infiltrate layer ,those disadvantage confined the apply extension .Cast infiltrating have many advantages such as simple technics,effective use of alloy element,special performance on surface of part,think surface alloy layer .however , In this technics we needs put alloy dope or block on the wall of mould ,it is difficult to operate .it is prone to bring pore,dregs,conglutinate grit and so on ,and it have roughness surface and low size precision .All those disadvantage made it only suit for cast which has simple configuration.Compared with traditional Cast infiltrating , the vacuum infiltration processing have the advantage of nonuse core , predigest working procedure , flexible design of cast figure, easy clear up, flat cast surface , achieve high mechanization .But this method need vacuumize equipment. The evaporative pattern casting infiltration processing (EPC) neither need vacuumize equipment nor have vice in surface alloy layer .this technic can apply to traditional foundry and no need bring in new technology personnel and new equipment.In this experiment, Tic wearable alloy layer on cast surface was prepared by EPC .surface alloy were implemented by this methods .This technic also studied structure and performance of alloy layer .Firstly ,choose matrix material wearable grain,adhesive,flux and confirm its proportion, and then smear mixed component and fire-resistant dope on EPS .Smear it on different surface, and the coating is also different .Finally, observe and analyse the structure of alloy layer, do wear–resistant experiment.We studied chemist component and microstructure of alloy layer by modernize analyse methods such as optical microscope, scanning electron microscope, laser scanning confocal microscope etc. Conclusions come out from those modernize analyse:1. According to the observe of surface macro-appearance ,we can see the macro-appearance which smear on top surface, left surface and right surface are good .But the macro-appearance were not flat when smear dope on underside of the sample .2. It is proved that smearing fire-resistant dope on coatings can prevent sands from cast surface, and the surface of cast was glabrous and flat.3. The thickness of coating influent the thickness of alloy layer , According to the study of difference thickness of sample S1,S2,S3,the coatings can not be infiltrated and melted by melt liquid when the coating is too thick ,the alloy layer was thin or none .During a thickness extension ,the thicker the coating the thicker the alloy layer ,when coating are thin relation to the thickness of cast ,it is does not meet the need of production .In this experiment, the size of grain is 1-3μm, 0.5mm is a ideality thickness of alloy .4. There are no obvious boundary between alloy layer and matrix by obverse the microstructure of alloy layer .compared the quantity of slice graphite in matrix with that of near alloy. it is indicated that infiltration took place between alloy layer and matrix .the liquor of gray cast iron had infiltrated to coatings ,the component in coatings was melted and then infiltrated to matrix .transition layer was formed between coatings and matrix ,in another word ,combine fashion between alloy layer and matrix is metallurgy combine .5. From the component analyse result, we can see that both alloy layer and transition layer have Ti element. It is all the more proved that infiltration took place between alloy layer and matrix, combine fashion between alloy layer and matrix is metallurgy combine.According to the contrast wear-resistant experiment of alloy layer and matrix, the compare of lose weight and wear appearance. Experiment results indicate:1. According to the obverse of wear appearance of alloy layer and gray cast iron matrix, we can see that grind wear and oxidation wear are the main wear mechanism of alloy layer; grind wear is the main ear mechanism of gray cast iron matrix.2. we can see from the lose weight of wear experiment under same count of wear ring that compare alloy layer to matrix wear–resistance obviously improved .when load is 150N ,wear rings are 4000,the wear–resistance performance of alloy layer is 7.4 times than that of gray cast iron .3. It can be see from the wear curve that the weight lose of alloy layer is light than that of gray cast iron matrix .its wear curve is basically beeline ,it shows the structure is uniformity inside alloy layer ,it is explains that the quality of alloy layer is good .In a word ,from the above study method we can see :it is successful to manufacture infiltration alloy layer by EPC methods ,it made the cast surface alloy come true ;smearing dope on top surface ,right surface or left surface can all form high quality surface alloy layer ,while dope can be break up by iron liquid when smearing dope on underside ;within an extension thickness of alloy layer ,the thicker of the coatings ,the thicker of the alloy layer ,but alloy layer can not form when the coating is too thick , when the granularity of wear–resistance is 1-3μm, 0.5mm is the best thickness for coating; he weight lose of alloy layer is light than that of gray cast iron matrix, the wear–resistance performance of alloy layer is 7.4 times than that of gray cast iron .