| 摘要 |
A ceramic glass body, formed from a heat-sensitive glass by controlled dentrification and which contains a metallic compound reducible to the metal state, is provided with a metallic film on the surface by heat treatment in a reducing atmosphere. The glasses used are as disclosed in Specifications 924,996 and 943,599 with the addition of copper, silver or gold compounds which are reducible to the metal. Water, up to 5%, may be added to the raw ingredients to assist in the reactions. The reducing gas may be hydrogen, forming gas (90% N2 + 10% H2) or other mixtures of N2 and H2. The reducing atmosphere may be maintained throughout the heat treatment or, preferably, an oxidizing atmosphere may be maintained during the initial low temperature procedure. In example, the temperature is raised at about 20 DEG C. per minute to the region of the melting-point of the glass and this maintained for at least 1 hour; then raised at less than 2 DEG C. per minute to 50-200 DEG C. above the Mg point and this maintained for at least 1 hour; the atmosphere is then purged with N2 and a reducing gas atmosphere substituted; the temperature is then raised at less than 5 DEG C. per minute to the final crystallization temperature, 850 DEG to 1,050 DEG C. depending on the glass, and this maintained for at least 1 hour. Cooling to room temperature at about 10 DEG C. per minute is then effected, the reducing atmosphere being maintained until the temperature is below 150 DEG C. Further ranges of temperatures are given for a different glass range. Immersion of the filmed article in dilute HF for a period of about 5-60 minutes appears to remove a superficial layer of insulating material and leaves a metallic layer of high electrical conductivity. The filmed bodies may be used as parts for ceramic to metal seals, for capacitors and also for printed circuit components, for which purpose the metal film is etched away from remaining areas, the circuit areas being protected by a suitable coating. |
