| 摘要 |
<p>1,164,888. Descaling; heat-treating ferrous materials; fluxes. COMBUSTION ENG. Inc. Oct.25, 1967 [Dec.12, 1966], No.48616/67. Headings C7E, C7M and C7N. A ferrous metal or alloy member is heattreated, whilst preventing and removing scale formation on the member, by applying to the member, e.g. by brushing, spraying or dipping, a descaling coating composition comprising a KC1 + NaCl salt mixture with refractory cement and water, heating the coated member above the critical (austenitizing) temperature e.g. to 1200‹ F., and quenching e.g. with air or water the heated coated member. The process is particularly for martensitic hardening without transformation to bainite, pearlite or ferrite. The composition comprises by weight 67-83% of the salt mixture and 17-33% of refractory cement (dry basis), equivalent to 63-80% of the salt mixture and 20-37% of refractory cement (wet basis e.g. containing 16-20% water). Preferably the salt mixture comprises by weight 30-55% KC1 and 45-70% NaCl, and the cement is an aluminium silicate based refractory. The coating composition may also contain boric acid and/or Na 2 B 4 O 7 , e.g. in amount of 3% by weight of the slurry.</p> |
