Study On The Preparation Of Ceramic-coat With The Serpentine

Based on the careful research to physical chemistry property and phase changecharacter of the serpentinite , we emphatically developed the following experiment:adopted serpentinite as main raw materials, through High-temperature fusion ,plasma-Spraying,electric-arc Spraying methods, Prepared the ceramic-coat on the metalplate. At the same time, we evaluated the phase composition,microstructure,physical andchemistry property of the ceramic coat.Chemical analysis indicates: the SiO₂ of the serpentinite is 43.49%,MgO is 44.0%.The result is close to the serpentine content in theory. Microstructure analysis find that theserpentinite is composed of the serpentinite aggregation(mass) which arrange a little rule insheet-board shape. DTA-TG analysis indicates that the serpentinite strip down the adsorbedwater in 147℃, and remove construct water in 598℃, at last become olivine in 817℃.The study finds that in 750℃ calcining the serpentinite 2 hours, the phase compositiondoes not change ,but it lose about one of thirds construct water, as well as 3.83-4.39% of itsquantity and volume shrink 1.32%, hardness reduce 0.8%;and lattice parameters change alittle like this: a0 is enlarged,b0 and c0 are smallness .Differently, in 820℃ calcining theserpentinite 2 hours, it become olivine with losing 10.84-11.22% quantity, shrinking 2.22%and the hardness is obvious strengthen.The High-temperature fusion experiment has confirmed the optimal materialcomposition and technic-condition of preparation of the ceramic-coat.The materialscomposition is 90% of the serpentinite and 10% of fluorite;the sinter atmosphere isnitrogen protection;and the sinter temperature is 1250℃, and the time of constanttemperature is 60 minutes. The test indicates that the composition of the coatis wustite andiron olivine;it has high micro-hardness, and it gradually reduces from the surface to theinner plate. The combine strength of the coat and metal plate is larger than 6.13 MPa;theheat resistant test indicates that the ceramic-coat is well, at below â–³T=500℃,it does notappear crack and spalling through 16 times heat-cold circle. The corrosion resistance isalso clear well than the carbon steel.Adopted the electric-arc Spraying method, the paper has also created the ceramic-coat,and has simply confirmed the technic-condition. Study finds that the coat is mainly madeup of slice structure, and it has sphericity grain and pore,air gap;the grating coefficient isclear lower than carbon steel of number 45, and it gradually reduces along with timeprolonging. The percent of loss is larger than the carbon steel of number 45.The paper also makes the phasm-Spraying experiment and performance evaluation ofthe coat. study finds the composition of the coating is olivine,and its structure is compact,less pore and air gap.the combine strength of the coat itself is 4.48 MPa, the combinestrength of the coat and matrix is well. Result indicates that it is feasible for adopting theserpentine to make the ceramic-coat on the metal matrix by phasm-Spraying method, but italso needs optimize the technic-condition.