DE1558515C3 - Use of a platinum-titanium alloy - Google Patents

Description

The glass industry requires numerous objects which, in use, come into contact with molten glass come. Such items are usually made of pure metals or alloys that have a have high heat resistance and are resistant to glass. Platinum and alloys are suitable for this of platinum and rhodium. The platinum has high strength while manufacturing various optical glasses, the stronger platinum-rhodium alloys cannot be used because the Rhodium discolors the glass.

The invention is now based on the object of proposing a platinum alloy with high heat resistance, in which there is no risk of discoloration of optical glasses. To solve this problem the use of an alloy with 0.5 to 4% titanium, the remainder platinum, is proposed as a material for objects, which come into contact with molten glass during use.

From P. E11 i ο 11, "Constitution of Binary Alloys", First Supplement, McGraw-Hill Book Company, 1965, pp. 751 and 752, is the platinum-titanium system known. In this context, however, nothing is said about the properties of the platinum-titanium alloys, in particular nothing about their heat resistance and resistance to glass.

If the titanium content is below 0.5%, the strength is the. proposed alloy is insufficient, while · ' Alloys with a titanium content of more than 4% can no longer be machined.

A sufficient criterion for the strength of the proposed alloys is the load ίο which ^{leads to breakage at 145O 0} C after 100 hours. This strength is highest at a titanium content of 1.25 to 1.75%, so that the titanium content of a preferred alloy falls within these content limits. Although it is a binary alloy in the present case, it can also contain impurities; however, the impurities frequently found in platinum and described below should not exceed the following maximum limits:
20th

0.2% palladium,
0.5% rhodium, ..
0.1% iridium,
0.05% ruthenium,
0.5% gold,

0.05% silver,
0.05% osmium,
0.2%, nickel.

The proposed alloy can be made by mixing platinum sponge or powder with 0.5 to 4% Titanium powder can be produced. The powder mixture is melted and closed in an inert atmosphere a block, which is subsequently hot-forged and depending on the intended use a billet, sheet metal or wire is deformed. The strength of the proposed alloy results from the table below, the strength values of which were determined on the basis of 0.5 mm thick sheets

alloy Load in kg / cm ²
with a service life of
100 hours at 1450 ^° C Tensile strength in kg / mm ²
after glow Tensile strength in kg / mm ²
after an 8 hour
Annealing at 1500 ⁰ C Pure platinum
Pt / 5.0% Rh
Pt / 0.1% Ti
Pt / 0.5% Ti
Pt / l, 5% Ti
Pt / 2.0% Ti 11.2
22.5
15.5
24.6
14.1 14.2
22nd
17.3
26.8
40.9 12.6
20.5
15.7
23.6

The second column of the table above shows the resistance of the test alloys at long continuous load and the temperature of the molten glass increases with increasing titanium content and then falls off again. The third column shows that an alloy with only 0.1% titanium has little is stronger than pure platinum, while the alloys with titanium contents of 0.5% and more have a larger one Have tensile strength than the platinum-rhodium alloy. The fourth column finally shows that the Tensile strength is essentially retained when the alloys are at operating temperature for an extended period of time being held.

Claims (2)

Patent claims: 1. Use of a platinum alloy with 0.5 to 4.0% titanium, the remainder platinum including melt-related Impurities as a material for objects that are in use with molten Come into contact with glass. 2. Use of an alloy according to claim 1, the titanium content of which, however, is 1.25 to 1.75%, for the purpose of claim 1.