Vitreous enamel for exhaust gas silencers of IC engines - where slip consists of aluminium powder mixed with alumino-borate frit contg. no silica

摘要

The exhaust gas system, and esp. the silencer, is coated with an enamel contg. Al powder and a glass phase which has compsn. (I) by wt. 8-12% Al2O3, 40-60% B2O3, 6-14% Na2O, 0-7% PbO, 6-11% CaO, 7-12% BaO, 2-6% MnO, 0.2% CoO, and 1%, esp. zero % SiO2. The glass phase may also contain fine Si, ZrSiO4, CrO3, and/or CuO. The pref. milled slip contains all pts.wt., 30-60 frit with compsn. (I); 5-60 Al powder, 0-8 Si powder; 0-10 CrO3; 0-10 ZrSiO5; 0-3 CuO; 0.5-3 bentonite; and 70-80 water. The slip is applied to the substrates, which are then baked at 800-950 degrees C. The enamel has good adhesion, and withstands, heat, thermal shock, corrosion and vibration. The enamelled parts can be welded, and can be repeatedly quenched from red heat into cold water without impairing the properties of the enamel.