Preparation And Dielectric Properties Of Metal-based /Crystalline Glass Composite Coating

With the advancement of modern materials science and technology and the continuous upgrading of the equipment manufacturing industry,a single material is often difficult to meet the high-performance requirements of some complex equipment,processes or working environments.Metal-based composites have attracted much attention because they have the dual properties of metals and other materials.Metal-based glass-ceramic composite coating is a combination of metal and glass-ceramic glass,two materials with different physical,chemical and mechanical properties.Corrosion and other characteristics.Research on the preparation conditions,preparation methods,and strengthening and toughening mechanisms of metal-based glass-ceramic composite coatings has become a hot topic in the field of materials research.Li2O-Zn O-Si O2 series glass-ceramics are widely used in the field of metal sealing materials due to their low softening point,high thermal expansion coefficient,adjustable in a wide range,good mechanical strength,and excellent electrochemical performance.In this subject,chemically pure reagents were used as raw materials.Li2O-Zn O-Si O2 series glass-ceramics were prepared by sintering method.The effects of different Ca O contents on the crystal phase types,crystallization effects,and microstructure of glass-ceramics were studied by DSC,XRD,SEM and other analytical methods.Electrochemical workstations were used to test the dielectric properties of glass-ceramic samples prepared with different Ca O contents under different experimental conditions.Based on this,the plasma spraying method and the coating and sintering method were used to conduct experimental research on the composite of glass ceramics and metal substrate Q235 steel,and the effects of different substrate pretreatment methods and composite time on the composite effect of the coating were analyzed.Further explore the mechanism of strengthening and toughening of glass-ceramic-metal matrix composites.research shows:(1)In a certain content range,Ca O can significantly promote the crystallization process of Li2O-Zn O-Si O2 series glass-ceramics.With the increase of Ca O content,the nucleation and crystallization temperature of the main crystalline phase Li2Si2O5 both decreased,and the precipitation of Li2Si2O5 increased with the increase of Ca O content.When the content of Ca O is 5%,and the sintering takes 660 ? as the nucleation temperature and 682 ? as the crystallization temperature,the precipitated Li2Si2O5 crystals are small in size,densely arranged,and the glass-ceramic is thedensest,and the sample has the best dielectric properties.,The resistivity can reach6.19×1010 ? · m.(2)The research process of composite of glass-ceramic and metal substrate shows that,under the conditions of this study,the coating and sintering method is more conducive to the composite of glass-ceramic and metal than plasma spraying.The proper pretreatment temperature of the metal substrate during the coating and sintering process is particularly important for the strengthening and toughening of the coating.Under the conditions of this experiment,the pretreatment temperature of the base metal was 500 ?,and the composite coating had a dense structure and the best combination effect at the time of nucleation and thermal insulation for 2 h and 1 h during the composite process,and the resistivity of the composite coating was the largest,which was 3.52×107 ? · m.At this time,the microstructure of the metal-based glass-ceramic composite coating showed a metal matrix-Fe O-Fe2O3-glass-ceramic gradient material structure.