| 摘要 |
<p>A vacuum-tight assembly, such as a discharge tube (40) for a sodium vapor arc lamp, includes a high density polycrystalline ceramic body, such as alumina or yttria, having a cavity (42), at least one closure member (44), and a sealing material (56). The closure member (44) is formed from a molybdenum-titanium alloy containing a small amount of nickel, cobalt, or copper. The nickel, cobalt, or copper forms a relatively low melting eutectic with titanium, thereby facilitating fabrication of closure members by sintering. The closure member (44) and the sealing material (56) have thermal coefficients of expansion closely matched to the thermal coefficient of expansion of the ceramic body over a wide temperature range.</p> |
