| 摘要 |
<p>PURPOSE:To provide a marking compsn. suitable for use in marking the surface of a high-temperature article, perticularly steel stock, containing boric acid, diammonium hydrogenphosphate and water. CONSTITUTION:A marking compsn. contains 10-20pts.wt. boric acid, 20-40pts. wt. diammonium hydrogenphosphate and water. The ammonium ion in the compsn. increases the solubility of boric acid, improves the wettability of the surface of a high-temperature article and plays a role of keeping the compsn. neutral. When the compsn. is applied to the surface of a high-temperature article, boron phosphate is instantaneously formed from boric acid and diammonium hydrogenphosphate, whereby a white mark is formed. Since boron phosphate is molten at 900 deg.C or above to form a transparent film and the mark disappears, it is desirable to use the compsn. at 900 deg.C or below. If desired, 10-20pts.wt. high-melting inorg. pigment may be incorporated in the compsn.</p> |
