DE1950468A1 - Palladium alloys resistant to molten - silicates - Google Patents

Abstract

Alloy comprising 10-30% Rh or Ir and/or 30-50% Pt, balance Pd. Composn. comprises 10-30% Rh, balance Pd; esp. 50% Pt, balance Pd. The alloys have a strength at 800 degrees C varying from 12.1-21.4 kp/mm2 and, at 1400 degrees C, 2.3-3-3.3 kp/mm2. As liner or crucible for holding molten glass mixtures, comprising oxides, esp. molten silicates, at 900-1300 degrees C. Gives a savings in costs by replacing Pt by Pd. A lime-sodium hydroxide glass melt was held for 135 h at 1200 degrees C in a crucible made of a Pd alloy of composn. 80% Pd, 20% Rh. The decrease in weight of the crucible was 259 mg; thickness decreased 27.8 mu m/a. The alloy had a resistance to deformation of 4.5 kp/mm2 at that temp.

Description

Use of palladium alloys for handling molten Oxide mixtures or glasses, in particular silicate mixtures.

When processing silicic acid-containing masses, such as rock masses, Slags and especially glasses in a hot state in which the masses melted or are doughy, high demands are placed on the action of such materials exposed materials of the melting or shaping equipment. You need to high chemical and mechanical resistance. as well as have a high melting point.

Deshalo is the use of base metals for lining ceramic containers or casing for ceramic tools for these purposes only possible in exceptional cases. Rather, precious metals and their alloys are used for this, spec. ni.edrizr alloyed Pt materials such as Pt / Rh 95/5 or 90/10%, used in large amount. A key factor that is often limited to the use of Pt materials is their high price. The further task in the development of precious metal materials for handling molten ones Oxide or silicate mixtures at high temperatures consists in putting them together in such a way that that the precious metal value per volume unit is a minimum. In this regard Palladium would be most beneficial because its price / 0 would be less than 250 »' of that of platinum. As the resistance of palladium under the conditions of the glass clay and its heat resistance at temperatures around 12000C, however, inadequate has only risked using palladium in quantities of 0.5-10% of the standard alloys Pt / Rh 95/5 and 90/10% to be added to the glass industry. The limitation of the palladium content was based on the assumption that higher contents improve the bastandiness and heat resistance affect the alloys unfavorably.

Surprisingly, it has now been found that at temperatures of 900-13000C the usability of palladium in glass melts due to additions of 20 and more Percent platinum, ithodium or iridium, singly or in groups; significantly improved can be. This applies, for example, to the alloys Pd / Rh 80/20%, Pt / Pd / Rh 50/40/10%, 40/40/20% and 30/50/20%.

Palladium alloys with 10-30% Rh and palladium alloys with 10-20% Rh and 30-50% Pt, preferably 10% Rh and 50% Pt, have proven particularly useful. For example, rods used in soda-lime glass melts of 13000C as "such alloys 2 with an immersed area of 15 cm after 170 h show the following changes in weight (Table 1) -melt of 13000C after 170 h. Alloy starting weight weight loss thickness loss mg g / m².d µm / a Pd / Rh 80/20% 76.14 # 0 # 0 # 0 Pt / Pd / Rh 50/40/10% 113.70 30 2.85 68 After 720 or 360 hours of use in a f 1 ie ß end (40t / d) glass melt of the same composition at 12800C, the same test rods according to Table 2 have 8, 9 or 0.45 g / m².d in weight lost with even removal corresponds to a decrease in diameter of 270 or 10.5 µm / a.

Table 2: Weight and arithmetic decrease in thickness of rods made of Pd alloy in flowing glass melt of 1280 ° C. Alloy Starting Use Weight Thickness HV 1 weight h acceptance decrease kp / mm² mg g / m².d µm / a Pd / Rh 80/20% 71.91 720 400 8.9 270 114 Pt / Pd / Rh 50/40/10% 107.41 360 10 0.45 10.5 106 The good dimensional stability of the alloys at 13000C is documented by the hardness values liv 1 = 114 or 106 kp / mm2 measured after use.

In a further series of tests, a soda-lime-glass melt was used from 1200 ° C 135 or 144 h in a crucible of 40 ccm each made of the two alloys held. With a wetted crucible surface of 50 cm, the in Table 3 below showed weight losses.

Table 3: Weight and arithmetic decrease in thickness of 40 ccm crucibles made of Pd alloys in which glass melts are kept at 12000C. Alloy Starting use Weight reduction Thickness from HV 0.5 weight gh mg g / m².d taking kp / mm² µm / a 80/20% 16.4126 135 259 0.92 27.8 111 Pt / Pd / Rh 50/40/10% 23.9623 144 285 0.95 22.5 104 The hardness measured after the crucibles have been used agrees well with that of the test rods.

The excellent resistance of the alloy Pd / Rh 80/20% against Soda-lime glass is also melted by the smoothness of the inner surface of a glass Evidence of the outlet pipe through which such a melt of 1200 ° C flowed for 233 h is, as the cross-section shown in Figure 1 shows. An analogous finding was made according to Figure 2 with a cross section through a crucible made of a dew alloy Pt / Pd / Rh 50/40/10% obtained by holding such a gel melt at 1200 ° C. for 144 h was.

Assuming that the high temperature strength of the Pd-containing alloys about that of the alloy that has hitherto been preferably used for the stated purpose Pt / Rh 90/10% should correspond to that between 20 and 1400 ° C from 6B = 28.7 to 2.6 kp / mm² decreases, this requirement is met e.g. by the following compositions (Table 4).

Table 4: High temperature strength of Pd-containing alloys according to the application.

Heat resistance 6 B at Alloy 20 ° 800 ° 1000 ° 1200 ° 1400 ° Pt / 10 Rh 28.7 12.1 8.2 4.7 2.6 Pd / 20 Rh 45.3 14.0 8.4 4.5 2.3 Pt / Pd / Rh 50/40/10% 41.4 14.5 8.4 4.2 2.3 40/40/20 54.0 21.4 11.4 6.2 3.3 30/50/20 41.4 14.2 10.8 5.8 3.1 In comparison, the known Pt / Pd / Rh alloys have significantly lower levels. Heat strengths (see Table 5).

Table 5: High temperature strength of known Pt / Pd / Rh alloys High temperature strength 6 B at Alloy 20 ° 800 ° 1000 ° 1200 ° 1400 ° Pt / Pd / Rh 85/10/5 28.5 9.5 6 3.25 1.75 90 / 5/5 27 9.5 6 3.00 1.50 90 / 3/7 28 10.3 6.75 4.2 2.5 (?) Due to their much lower spec. Weight are the alloys according to the application above. In addition, it is noticeably cheaper than Pt / Rh 90/10%, as can be seen from Table 6 below: Table 6: Specific weights of Pd-containing alloys according to the application. Alloy spec. Wt. p / ccm Pt / Rh @ 0/10% 20.0 Pd / Rh 80/20% 12.1 Pt / Pd / Rh 50/40/10% 15.4 40/40/20 14.7 30/50/20 13.7 In addition, the g-price of the Pd is less than 25% of that of the Pt.

Claims (3)

P a t e n t a n s p r u c h e 1. Use of Pd-containing alloys for objects for handling molten oxide mixtures or glasses, in particular Silicate mixtures, at temperatures of 900-1300 ° C, consisting of 10-30% Rh or Ir and / or 30-50% Pt, remainder Pd. 2. Use of a Pd-containing alloy according to claim 1, consisting made of Pd with 10-30 Rh. 3. Use of a Pd-containing alloy according to claim 1, consisting of 10-20% Iul, 30-50% Pt, remainder Pd, preferably 10% Rh, 50% Pt, remainder Pd.