| 摘要 |
<p>A wire, mainly of nickel, for directly-heated cathodes, includes a proportion of a refractory oxide, e.g., alumina, thoria, or magnesia exceeding 0.03 per cent., e.g., 0.1 to 0.3 per cent. Finely-divided pure nickel powder, e.g. produced from the carbonyl or freed from carbon by sintering in wet hydrogen, may be mixed with a solution of aluminium nitrate sufficient to give 0.1 to 0.3 per cent. alumina when dried and heated to 650 DEG C. in wet hydrogen. The product is mixed with sufficient powdered aluminium alloy, containing 40 per cent. nickel, to give 0.4 to 2 per cent. free aluminium, pressed and sintered in hydrogen free from oxygen, or in vacuo at 1350 DEG C. for 1/4 to 1/2 an hour. The bar thus produced is pressed cold, re-sintered, rolled or swaged, and drawn.</p> |
