Aluminium titanate ceramic burner plater for flat gas burner - has good resistance to corrosion and thermal shock and low thermal conductivity

摘要

Burner plate (12) for a flat burner (2), having orifices (12) for fuel gas (4) distributed over the surface, consists of an Al2TiO5 ceramic (I). Pref. (I) is stabilised by adding SiO2, ZrO2, MgO, Fe2O3, Na2O and/ and/or CaO. It has a coefft. of thermal expansion of ca. O +/-1 x 10power(-6) K. The orifices have a cross-section of 0.7-7, pref. 1.7-5 mm2 and are cylindrical, pref. with a conical taper. The plate is 4-10 mm thick. It is made from a mixt. contg. TiO2 and Al2O3. The pref. compsn. of the starting material is 50-55 (wt.)% Al2O3, 30-35% TiO, 5-10% SiO2, 1-5% ZrO2, 0.5-5% MgO, 0-1% Fe2O3, 0-1% Na2O and 0-0.2% CaO. The plate is produced by moulding the mixt. of starting materials; consolidation, pref. to a density of 1.8-2.3 g/cc; and sintering, pref. for 2-3 hrs. at 1450-1550 deg. C. The mould has pegs to form the orifices and the mixt. is pressed with a plate with holes corresp. to the pegs. ADVANTAGE - The burner plate is more durable than metal plates, which are corroded by impurities, esp. chlorohydrocarbons in the gas, and allows the min. flame temp. to be reduced. It has a very low coefft. of thermal expansion, which (almost) eliminates thermal strain and gives high resistance to thermal shock, preventing the formation of microcracks. The low thermal conductivity ensures that the back of the plate remains relatively cool, preventing back-firing.