|
Self-propagating High-temperature Synthesis （SHS） is a new technique making use ofthe heat from the chemical reaction between reactors for preparing materials. GravitationalSHS separation technique is used for mading composite pipe lined ceramics, which isattentioned extensively by the academic field. The toughness, property of thermal shockresistance and density are not good enough for the application of the composite pipe.To solve this problem, this topic use gravitational SHS separation technique to madecomposite pipe lined （ZrO2+Al2O3） multiphase ceramics, and establish orthogonal experimentfor optimizing the content of ZrO2, NaF, SiO2in order to attain excellent integratedperformance, which are microhardness, porosity, property of thermal shock resistance and KIC;Studying on the ZrO2stabled by Y2O3effect on microstructure, physical and mechanicalproperties, interface of bonding of the composite pipe;The composite pipes of the samecomposition of the reaction materials are respectively processed with normalization, quencher,furnace cooled and horizontal mechanical vibration when the materials is reacting, andresearch the change of the microstructure and physical and mechanical properties.Studies have shown that the optimal composition from the orthogonal experiment is10%ZrO2、4%NaF、2%SiO2.The microhardness of the ceramic coating is1273.8Hv. Porosityis5.34%, Property of thermal shock resistance is14.KICis15.37MPa.m1/2.The content ofZrO2have a significant impact for microhardness, porosity, property of thermal shockresistance and KIC.When the content of ZrO2is10%, the microhardness have maximum.Porosity,property of thermal shock resistance and KIChave a maximum when the content ofZrO2is20%.The microstructures respectively are seperated eutectic, rodlike crystal, lamellar androdlike crystal as the content of ZrO2is10%,20%,30%,40%. The content of the ZrO2stabled by Y2O3is10%,20%,30%and the microstructures respectively are seperated eutectic,radial pattern and snowflake. The bonding between steel substrate and ceramics coating of theZrO2stabled by Y2O3is superior to ZrO2non-stabled. Relative to ZrO2non-stabled, propertyof thermal shock resistance of composite pipe of ZrO2stabled is strengthen, while microhardness, porosity and KIChave a little fall.Studying on the different technological parameter influence in microstructure andphysical and mechanical properties with the content of10%ZrO2,2%NaF,2%SiO2andthermit. Ceramics disposed with normalization has a distinct columnar crystal, while ZrO2and glass phase is distributed on the boundary area of the Al2O3dendrite. In ceramicsquenched Al2O3is isometric crystal, and ZrO2is distributed on the Al2O3crystal boundary inappearance of floccule.ZrO2in furnace cooled ceramics has a bigger size, and is distributedequably; Columnar crystal is destroyed when horizontal mechanical vibration is added, andeven changed to isometric crystal. Relative to normalization, ceramics disposed with differentmedia, Microhardness is improved slightly, and property of thermal shock resistance isimproved greatly, especially disposed with horizontal mechanical vibration; The porosity ofceramics quenched increase, while furnace cooled ceramics and horizontal mechanicalvibration decrease.KICis slightly receded with horizontal mechanical vibration disposition,and a great receded with quencher and furnace cooled ceramics disposition.
|