铝碳质长水口用无铝抗氧化涂料的研制

Preparation of alumina-free antioxidation coatings for alumina carbon long nozzles

以硅砂、硼砂、Na 2O为主要原料,以水玻璃为结合剂,钠基膨润土为悬浮剂,研制了铝碳质长水口用无铝抗氧化涂料。结果表明:1、当Na 2O、硅砂、硼砂的质量分数分别为15.0%、42.5%、42.5%时,硅砂-硼砂-Na 2O混合料的半球温度为719℃,满足涂料的设计要求。2、当水玻璃加入量为30%~40%(w)时,经800℃保温2 h后,涂料能在长水口表面形成较完整光滑的釉层;而当涂料中的水玻璃加入量增加到50%~60%(w)时,釉层不完整,水口表面裸露很多。3、随着涂料中水玻璃加入量的增大,长水口试样氧化后的质量变化率呈先减小后增大的变化趋势,水玻璃溶液加入量为40%(w)时最小。4、从SEM照片可以看出,水玻璃加入量为40%(w)时,涂层厚度较厚,与基体结合较紧密。

The alumina-free antioxidation coatings for alumina carbon long nozzles were prepared using silica sand,borax and Na 2O as the raw materials,water glass as the binder and sodium bentonite as the suspension agent.The results show that when the mass fraction of Na 2O,silica sand and borax is 15.0%,42.5%,42.5%,respectively,the hemispherical temperature of the silica-borax-Na 2O mixture is 719℃,which meets the design requirements of coatings;when the water glass addition is 30%-40%,by mass,after heating at 800℃for 2 h,the coatings can form a relatively complete and smooth glaze layer on the long nozzle surface;however,when adding 50%-60%water glass,the glaze layer is incomplete and the nozzle surface exposes a lot;with the increasing water glass addition,the mass change rate of the long nozzle specimens after oxidation decreases first and then increases,reaching the minimum by adding 40%water glass;meanwhile,the SEM photos show that when adding 40%water glass,the coating is thick and bonds with the substrate tightly.