US2067569A - Heat resisting implements - Google Patents

Description

Patented Jan. 12, 1937 HEAT RE SISTING IMPLEMENTS Werner Hessenbruch, Hanau-omthe-Main, Ger

many, assignmto firm Heraeus-Vacuumschmelze Aktiengesellschaft, Hanau-on-the- Main, Germany No Drawing. Application March "l, 1935; Serial No. 9,806. In Germany March 24, 1934- 1 4 Claims.

This invention relates to heat-resisting implements constructed from alloys of metals of the iron group and the sixth group of the periodic system of the elements.

5 The heat resistance of implements constructed from alloys of metals of the iron group and the sixth group of the periodic system of the elements, e. g. constructed from chrome-nickel alloys is to be ascribed in the first place to thefact that the high chromium content in. association with nickel forms a strongly adherent oxide layer which protects the remaining metal from burning. It was formerly supposed that the heat resistance of implements constructed from such alloys could be considerably improved when elements more electropositive than nickel, the

. oxides of which are stable above 1500 C. were added thereto. It has, however, been shown that these considerations are'by no means generally applicable and that although certain of these electropositive elements increase the heat resistance, others on the contrary do not. Thus, for example, the heat resistance of an implement constructed from a chrome-nickel alloy is con- 35 siderably reduced by addition of titanium or also vanadium; even additions of aluminum bring about improvements of the heat resistance only under particular conditions, whereas in small quantities they have disadvantageous in- 30 fluences. Since titanium and aluminum are nearly related to the rare earths, it was consequently to be expect-ed that the latter analogously with the former elements would behave in a similar manner, that is to say would not give rise 35 to any increase in the-heat resistance of implements made of chrome-nickel alloys. Thorough research has now shown that these rare earth metals in contradistinction to titanium and aluminum have the property of increasing to a con- 4 siderable extent the heat resistance of implements constructed from alloys of metals of the iron group and the sixth group of the periodic system ofthe elements, e. g. constructed from chrome-nickel alloys. Thus, for example, the life of a 0.4 mm. wire in the form of a small spiral wound on a 3 mm. mandrel heated electrically to 1050 C. for alternate periods of two minutes with interposed breaks of 2 minutes, was about 120 hours. A similar wire made of the 50 same alloy with an addition of- 0.2% of cerium or-0.2% of cerium mixed metal 1. e. cerium mixed or alloyed with other metals of the rare earths had a life period of about 200 to 280 hours. Higher percentages of cerium give a 55 corresponding increase in improvement except that with larger additions the efiect is not wholly proportional to the amount introduced, a content of about 0.8-1% of cerium or cerium mixed metal giving about the maximum efiect a content of 1.2% being the upper limit coming into 5 consideration.

The additions of metals of the rare earths required for obtaining an appreciable increasing of the .life period of heat resisting implements such as heating wires or bands for electrically 1o heated furnaces, construction elements of the inner partsof heating and annealing furnaces,

e. g. conveying chains, supporting sheet metal, pyrometer protecting tubes &c, need be very small, inasmuch as additions of 0.02 percent of 15 rare earth metals to the molten base metal or a content of 0.01% in the final alloy already suflice to give a noticeable effect. The base metal for the heat resisting implements to which the rare earth metals are added may contain 20 besides metals of the sixth group of the periodic system of the elements metals of the iron group as the main constituent, namely 50 to 98% of nickel, and up to 48% of iron or iron plus cobalt, the amount of cobalt not exceeding 20% of the final alloy. The percentage of the metals of the sixth group of the periodic system of the elements namely chromium, molybdenum, tungsten and uranium may amount to 1 to 48%, the chromium contents being 1- to the amount of each of the metals molydenum, tungsten and uranium should not exceed 20%. When several of the elements cobalt, molybdenum, tungsten and uranium are contained at the same time in V the alloy, their sum should not exceed 20%. The alloys may further contain small additions for deoxidatlon or for improving the malleability such as manganese, magnesium or silicon, each up to an amount of 2%, the sum of these additions not exceeding 2%.

I claim:

1. As an article of manufacture and trade a heat resisting implement constructed of a chromium-nickel alloy comprising main and auxiliary elements, the main elements consisting of from to 98 p. ct. of nickel, from 1 to 30 p. ct. of chromium, from 9.01 to 1.2% of metals of the cerium group, from a small but efiective amount to 20% of cobalt, the auxiliary elements consisting of from a small but effective amount to 20 0 p. ct. of metals of the sixth group of the periodic system, besides chromium, and the sum .of the cobalt and the last-named metals amounting to 20% at most.

2. As an article of manufacture and trade a named metals amounting to at most.

3. As an article of manufacture and trade a heat resisting implement constructed of a chromium-nickel alloy comprising main elements and an auxiliary element, the main elements consisting of from 50 to 98 p. ct. of nickel, from 1 to p. ct. of chromium, from 0.01 to 1.2% of metals of the cerium group, from a small but eflective amount to 20% of cobalt, the auxiliary element being molybdenum. from a small but effective amount to 20% and the sum oi cobalt and molybdenum amounting to 20% at most.

4. As an article of manufacture and trade a heat resisting implement constructed of a chromium-nickel alloy comprising main elements and an auxiliary element, the-main element consisting of from to 98 p. ct. of nickel, from 1 to 30 p. ct. chromium, from 0.01 to.1.2% of cerium, from a small but effective amount to.20% of cobalt, the auxiliary element being molybdenum from a small but effective amount to 20% and the sum of cobalt and molybdeum amounting to 20% at most.

. WERNER HESSENBRUCH.