DE2002886A1 - Process for the production of a material which is dispersion hardened by internal oxidation - Google Patents

Description

GERMAN GOLD AND SILBEIT SCTTEIDEANSTALT FORMERLY ROESSLER Prankfurt / Main, Weißfrauenstrasse 9

Process for the production of a dispersion hardened material by internal oxidation Material.

The invention relates to a method for producing dispersion hardened Materials made of platinum metals and gold or their alloys, which act against both oxidizing and reducing or inert gases and are stable in a high vacuum.

Precious metals and precious metal alloys, in particular platinum metals and platinum metal alloys, find extensive use in those cases where there is a need for high resistance to Corrosion or against oxidation at high temperatures. However, a disadvantage of these materials is that they are relatively low Strength at high temperatures.

There has therefore been no lack of attempts to test the noble metals and their alloys by adding them in an oxidizing atmosphere To harden and solidify inert substances, such as high-melting oxides.

For example, it is possible to mechanically mix fine-grained platinum powder with fine-grained powder of high-melting oxides and this mixture on powder metallurgy we ^ e to to process. The reproducibility of the property values of a The material obtained in this way is, however, not very satisfactory, and the improvement of, for example, the creep strength of a such material at high temperatures compared to materials without additives is only relatively low.

1 0 9 H 3 1/1 2 U BAD ORIGINAL

It is also known, the introduction of the hardening particles by simultaneous precipitation from salt solutions, by evaporation of Carry out solutions that contain both components or by spraying such solutions in flames. Further procedures are the superficial oxidation of alloy powders or the common Deposition from solutions by a combination of galvanic deposition and electrophoresis.

fe All of these procedures have the disadvantage of being carried out relatively cumbersome and costly without being an essential one A ^ improvement of the property values can be achieved.

It has recently been proposed that the creep rupture strength of platinum metals at high temperatures be increased significantly by dispersion hardening by internal oxidation at temperatures between 900 and 10000 after alloying with a metal, the oxide of which has a very high heat of formation. In addition to higher tensile strengths and hardnesses at room temperature, higher creep strengths at higher temperatures can also be achieved by this method.

^ The diameter of the oxide particles thus produced by internal oxidation is, however, of the order of magnitude of a few μm, so that the dispersion hardening efficiency that can be achieved by them is only relatively low. Thus, for example, in platinum with 1 £ zirconium ^f after the internal oxidation microhardness values of IIA 0.015 = 80 to 120 kgf / mm "erzidt, · at a Platinlegieruntr with 10 ^C O rhodium and 1 Ί zirconium according to the internal oxidation V.'erte of

r>

145 to 200 kp / min ". This is considerable compared to pure platinum Increased hardnesses, however, already fall on annealing at 1'00 ° C

2 drops sharply after a short period of time, at Pt / lZr to about 70 - bü kp / mm, at Pt / 10ith / lZr to about 120 to 130 kp / mm ".

109831/1214 BATH ORIGINAL

A major disadvantage of all known methods of hardening platinum metals and their alloys by adding high-melting oxides, however, is that the materials obtained in this way can only be used at higher temperatures in an oxidizing atmosphere. If it is used in a reducing atmosphere, a reaction occurs in the sense that the embedded oxide is at least partially reduced and the metal formed by the reduction is absorbed by the platinum or the other platinum metals with the formation of an alloy. As a result, however, the hardness and strength-increasing effect of the oxide particles is lost again. The gases released during the reduction also cause strong bubbles to form in the material and on its surface, which again greatly reduces the strength. Similar conditions arise when they are used under a high vacuum or in an inert atmosphere.

It was therefore the object of this invention to find a method which allows a dispersion-hardened platinum metal material to produce at high temperatures against both oxidizing and reducing and inert gases or is no longer sensitive in a high vacuum and retains its high hardness and creep strength.

It has now surprisingly been found that a material made of platinum metals or gold, individually or in groups, with the addition of one or more elements, with the addition of one or more elements, the oxides of which is a material made of platinum metals or gold which is resistant to high temperatures in oxidizing, reducing or inert gases or in a high vacuum, can be dispersed hardened by internal oxidation have high heat of formation, is obtained when the internal oxidation takes place at temperatures of 300 to 800 ⁰ C and then a thermal aftertreatment is carried out for stabilization. Advantageously, the internal oxidation takes place at 500 to bOO ° C instead of, preferably at 650 to 75O ⁰ C.

1 0983 1/1 21 A

BATH, QRIGINAL

Jiui ■ ■

The internal oxidation process according to the invention provides very fine-grained oxide precipitates, most of which are no longer optically resolved, but only resolved by an electron microscope can be. The diameters of the oxide particles are in the range from 1 μm down to <0.1 μm. With this finely dispersed Precipitation is linked to a very strong IT hardness and increase in strength, which is retained even at high temperatures.

fe to the internal oxidation is followed to stabilize the Material at high temperatures in oxidizing, reducing or inert gases or a thermal aftertreatment in a high vacuum at.

If the dispersion-strengthened material is used later only in an oxidizing atmosphere, one can this thermal after-treatment in an oxidizing atmosphere at 800 to 1 200 ° C, preferably at 900, to perform up to 1 100 ⁰ C. The oxidizing gases used for the internal oxidation and / or the thermal aftertreatment are, in particular, air and oxygen, it being possible to work either under normal or under increased or reduced pressure.

This aftertreatment in oxidizing atmospheres further improves the hardness and creep strength at high Temperatures reached.

Should the dispersion-hardened material be used later in reducing, inert or composition-changing atmospheres or in a high vacuum, the thermal aftertreatment is carried out in reducing gases at temperatures from 600 to 1,600 ° C., in particular at temperatures from 100 to 1-500 ° C., carried out.

- 5 -

109831/1214

Particularly advantageously, the temperature range of 1 OOO ° C to 1400 ⁰ C. The reducing gases is in particular hydrogen, carbon monoxide, coal gas or ammonia can be used. Under certain circumstances, the thermal aftertreatment can also take place in inert gases or in a high vacuum.

The thermal aftertreatment can be either separately or advantageously in combination with the further processing of the hardened material. The increased ones remain Hardness and strength values that the material exhibits after sole oxidation treatment, regardless of whether that Material is used in an oxidizing, inert or reducing environment. Also an ongoing change between the named ones Environments will be endured flawlessly without blistering or other damage.

The production of the alloys according to the invention can be either take place directly over sheet metal or wire and, to shorten the oxidation times, preferably over powder of the corresponding Alloys. It has proven to be particularly advantageous to use a starting material that has strong internal tensions, how they can be produced, for example, by cold forming. It is therefore preferable to use a jiilver made by mechanically crushing a compact alloy body.

Be j_sj2 i e l_l ±

Powders with grain sizes between approx. 100 and 300 / Ui: i were produced from alloys made of PtIZr, Pt / 9, 5Pd / lZr and Pt / lOIlh / lZr. This powder \ * urde I36 hours at 75O ° C oxidized in the air and subsequently after-treated for 15 hours at 1000 ⁰ C in air. After this treatment, the powder was cold-pressed at k t / cm for 1 hour

109831 / 12U BATH ORIGINAL

1400 C sintered in air and hot-rolled at 1 20O ⁰ C to sheet of 0.5 mm thickness. The metal sheets then had the following hardness values (HV 0.5) in the above sequence at room temperature: 230, 22b, 255 (kp / mm ² ).

Exposure to air for 1 hour at 1,400 ^° C. only resulted in a drop in hardness to 205, 207 or 235 (kp / mm). A further paging up to 500 hours at 1400 ⁰ C in the air did not further Tlärteabfall more. The pure alloys without ZrO _Q content only have the following hardness values after appropriate production and treatment: 50, 60 or 80 (kp / mm). So there has been a substantial permanent increase in hardness.

Example 2:

One cast bolt each of the alloys mentioned in Example 1 was machined on a lathe. The turnings obtained were treated in the same way as in Example 1 and processed into wire of 1 mm ^ by hot rolling at 1,200 ° C. and subsequent cold drawing. After annealing for 1 hour at 1,400 ° C. in air, the following tensile strengths at room temperature were obtained: Pt / lZr: 48 kp / mm ² , Pt / 9, 5Pcl / lZr 45 kp / mm ² , Pt / 10P.h / lZr : 65 kgf / mm ² . The tensile strengths of material without ZrO ₉ - \ npart are (in the same order) 15, "0 or 30 kp / ηιπΓ. For comparison, a value taken from the literature for a Pt / lORh set with Th0" is mentioned after 1 hour at 1400 ° C

ο
Strength of 36 kn / mm ~. This value is therefore considerably lower than for the internally oxidized platinum produced according to the invention without the addition of an alloy, while a Pt / IORh alloy using the original invention has almost twice the tensile strength.

109831/1214 ORIGINAL BATHROOM

Powder of the alloys of Pt / LZR and Pt / lORh / LZR 100 Stunaen were hot oxidized ⁰ 70o C in air and then annealed for 10 hours post-treatment hoi 1 ⁰ 00o C in air. From this material rods were pressed, sintered and processed warm or cold into wire of 1 ma tf . Creep tests at 1,400 ^° C. were carried out in air with this material. Figure 1 shows the results in a double logarithmic representation. The numbers attached to the individual straight lines mean: (T) Pt / 10! Lh / lZr, produced according to the invention, (V) Pt / lZr, produced according to the invention, (3} values taken from the literature for a with ThO ₀ Hardened Pt / 10JIh (produced by joint precipitation), (5 ") Pt / 10ORh without additive, QQpt phys. pure.

It can be seen from FIG. 1 that the alloys according to the invention are superior to all comparison materials in two respects are. On the one hand, for a required time until breakage, the load borne is generally greater than with the comparison materials, where (J ^ indicates the best values known so far, for the other is the slope of the straight line for those produced according to the invention Samples much smaller than the comparison materials. This means that the manufactured according to the invention Alloys behave unso better in comparison to the other samples, the longer the time required to pruck.

The 100 hour creep strength for the alloys (] P) and (aj, both produced according to the invention, is 5.2 and 3.6 kp / mm, for (5> only 1.1 kp / mm ", for (h)) even only Q, 5'i kp / ιππΓ ", which corresponds to an improvement compared to (2) by about ten times, compared to © by about five times. Extrapolating to 100,000 hours, the numerical values are (in the same order) 3 , 5; 2, b;

0.32 and 0.115 kp / i'iin ", which is an improvement of 32 times opposite (T) bxw. eleven times that of 0).

109831 / 12U

Example 4:

Powders with grain sizes between 100 and 300 μm were produced from molten alloys Pt / IZr, Pt / 9, 5Pd / IZr and Pt / 91ih / IZr. The thus powders were 136 hours hei 75 ^f) C oxidized in air, and then divided into two parts. The one part (a) was 15 post-treated in the air at 1 000 ⁰ C, sintered at 4 t / cm "" cold pressed, 1 at 1400 ⁰ C in the air and warm at 1200 ⁰ C in the air to plate 0.5 mm thick rolled out. The other part (b) was sintered directly with 4 t / cm cold pressed, 1 at 1400 ⁰ C in hydrogen and also hot rolled at 1200 ⁰ C to sheet of 0.5 mm thickness, said heating 1 200 ⁰ C also took place _{under IT 2.} The sheets then had the following hardness values (IP / 0.5 in kp / mm) at room temperatures in the above order: (a) 230, 228, 255 (b) 225, 230, 250.

An aging of 1 at 1,400 ^° C. in air resulted in both

Series only show a drop of about 20 to 30 kp / mm. A longer paging up to 500 at 1400 ⁰ C in air showed no further decrease in hardness more. Aging of both series for i at 1400 ° C in hydrogen gave the following hardness values (in the same order):
(a) 110, 105, 125 (b) 200, 198,215.

In addition to the sharp drop in hardness, a strong blistering. A further aging of 20 at 1,400 ° C in hydrogen resulted in another hardness drop in series (a) by about 20 to 30 kp / mm and increased blistering, bej of series (b), on the other hand, no longer drops in hardness.

Example 5 :

Chips of the same alloys were as in Example 1 after oxidation treatment of 100 ^hours at 700 ⁰ C in the air for long part l6 treated at 1000 ° C and sintering and hot rolling

109831/1214 " ⁹ "

processed into sheet metal in air (series a), partly ^{sintered after annealing of 2 at 1 00O 0} C in CO gas under CO and processed into sheet metal (series b). After these treatments, the hardness values of both series were again around 220 to 250 kp / inch. An annealing of 2 at 1 2CO ⁰ C under 10 "^ Torr, or 1 at 1 400 ⁰ C in hydrogen, or 2 at 1 400 ⁰ C in CO left the hardness of the samples produced without aftertreatment under CO

ο
again to a value of 100 Ms I30 kp / mm "with simultaneous strong blistering, while the hardness of the samples that had been post-treated under CO was practically unaffected.

One cast bolt each of the alloys mentioned in Example 1 was machined on a lathe. Some of the turnings obtained were oxidized in air at 700 ° C. for ^{100 hours} and post-treated in air at ^{1000 ° C. for 16 hours (series a).} Τ ·] ίη further part of the turnings of each alloy was oxidized in air at 700 100 ° C, followed by a GliiJibehancllung of 0 at 700 ⁰ C in hydrogen (Series B). Thereafter, v-ere both series by pressing, sintering at 2 1 400 ° C in air, V. ^r armwalzen processed cold rolling and cold drawing, to wire of 1 mm $. After annealing I ¹ at 1,400 C in air, the following tensile strengths (kp / niin) were found at room temperature:

Series a) Pt / lZr 4ö, Pt / 9.5Pd / lZr 45, Pt9Tlh / lZr 64 Series b) Pt / lZr 51, Pt / 9.5Pel / lZr 44, Pt / 91th / lZr 67.

After an additional annealing of both series of B at 1,400 ° C The following values were obtained in hydrogen (in the same order):

Series a) 14, 18, 27 Series b) 49, 42, 64.

~ 10 109831 / 12U

BATH ORIGINAL

While the tensile strength of those manufactured without reducing post-treatment Samples even falls below the values of the pure materials without the addition of Zr due to the formation of bubbles, the values remain the same of the specimens post-treated with reducing effect practically unchanged.

Example_7: _

The alloys Pt / lZr and \ 't / ^ Rh / l? .R were melted, 2 at

ο - "5
1 100 C homogenized under 10 Torr and processed to ΡιιΙλ he. A portion of the powder was oxidized 10C ^h at 700 ⁰ C in air and then 10 1 000 C in the air treated (Series A). Another portion of the powder was 100 oxidized at 700 C in air and treated at ⁰ C in hydrogen 1'OCO then 2. ¹ Both powders were then pressed, sintered, hot forged, hot rolled, cold rolled and drawn to wire of 1 mm 0th The equations for series a) were carried out in air, those for series b) under hydrogen. With the wires obtained, creep tests were carried out at 1400 ° C. in air, the material being used once in the drawn state, and secondly after annealing of b at 1400 ° C. in hydrogen. These tests resulted in the following} -load values (in Up / mm ") for times to break of 10 or 100 ^h :

I. Use hard drawn:

Series a) Pt / lZr ". = 4.0; ^ = 3.5

"10 ¹ V) O

Pt / 9Uh / lZr S _nh = 5.7; ^ n _{] ü (J} h = 5.0

- 11 -

109831/1214 BAD OWQiNAL

- li -

Series b) Pt / lZr y ^ _n = 3, B; ^^ = _3i3

Pt / 9Uh / l.7r <. _ _{ς 4} . ^ _nh "lO ~ ^P " 100

II. Insert after 8 at 1 40O ⁰ C in hydrogen:

Series a) Pt / IZro,. = 1.1; 6 ' _h = 0.6

U ₁₀ H ^D iü0 ⁿ

Pt / 9Hh / lZr, J. = 1.3; Ο " _nh = 0.9 " l 0 ^{n 1J} 100 ⁿ

Series b) Pt / lZrcr. = 3.7; σ _{η h} = 3.3

^iJ 10 ^{n 1Y} 100 ⁿ

^ r J ". = 5.2; ο ' _nh = ^w 10 ^nu 100

The flawless behavior of the alloys produced according to the invention is also evident in the creep resistance or after use in a reducing atmosphere.

Example 8;

Powder of the alloy Pd / Ag / Al / Zr 75 / 23.5 / 0.5 / 1.0 wt. # Was oxidized in air at 600 ° C. for ^{150 hours and then divided into two parts.} One part (batch a) was ^{aftertreated 20 * at 1,000 °} C. in air, pressed, sintered 1 at 1,350 G in air and first rolled out warm, then cold into sheet metal 0.5 mm thick. The other part (batch b) was pressed directly and 1 sintered at 135O ° C under hydrogen and also rolled out first warm under hydrogen, then cold to sheet metal 0.5 mm thick. Then pointed

- 12 -

1 09831/1214 BADOWQWAL

the sheets have a hardness (UV 0.5) of approx. 170 kp / mm. A storage of both batches for 1 at 1,400 ^° C. in the air

resulted in a drop in hardness to approx. 140 kp / mm. An additional annealing 5 at 1400 ⁰ C under hydrogen yielded in batch a) a \> reiteren drop in hardness to about 80 kgf / mm ", while the hardness of Batch B constant) remained. In addition occurred at batch a) a strong formation of bubbles, which was not the case with batch b).

Of course, the method according to the invention is not open Platinum and its alloys are limited to other precious metals, but in the same way palladium, rhodium, iridium, Ruthenium or gold or their alloys are dispersion hardened.

The platinum metals or the gold can be next to the elements, their Oxides have a high heat of formation, of course others as well Metals, such as silver or copper, can be added.

Not only zirconium, but also other elements whose oxides have a high heat of formation, such as titanium, thorium, hafnium, beryllium, aluminum or tantalum, individually or in groups, are suitable as hardening additives to the noble metal alloys mentioned. The contents of the added oxide-forming metals are generally between 0.1 and 5 ', Ό, preferably between 0.5 and 2 f-.

- 13 109831/1 21 A-

Claims (1)

PATENT CLAIMS 1. Process for the production of a dispersion hardened by internal oxidation, Resistant even at high temperatures in oxidizing, reducing or inert gases and in a high vacuum Material made of platinum metals or gold, individually or in groups, with the addition of one or more elements, their Oxides have a high heat of formation, which means that that the internal oxidation takes place at temperatures of up to 800 0, in particular at temperatures of 500 to 800 C, and then one for stabilization thermal post-treatment takes place. 2. The method of claim 1, dajdurjchgelcennz ^ eicnnet that the internal oxidation in Temperaturberjicli of 650 to 75O ⁰ C is carried out. 3. The method according to claim 1 and 2, dadiirjoh Sfcjiennzeichiiet that the thermal aftertreatment takes place in an oxidizing atmosphere at temperatures of 800 to 1 200 ⁰ C, in particular in the temperature range of 900 to 1 100 C. k. Process according to Claims 1 to 3, characterized in that the internal oxidation and / or the thermal aftertreatment is carried out in air or oxygen under normal, increased or reduced pressure. 5. The method according to claims 1 and 2, characterized in that the thermal aftertreatment is carried out in a reducing atmosphere at temperatures of 6θυ to 1 600 ° C, in particular in the temperature range of ⁰ bOO 1 500 C. - lh - 109831/1214 ORIGINAL BATHROOM 6. The method according to claims 1, 2 and 5, characterized in that the thermal aftertreatment in reducing Atmosphere carried out at temperatures of 1,000 to 1,400 ° C will. 7. The method according to claims 1, 2, 5 and 6, characterized in that that hydrogen is used as the reducing gas. β. Process according to Claims 1 and 2, characterized in that that the thermal aftertreatment in inert gas or in a vacuum is carried out. 9. The method according to claims 1 to 8, characterized in that that the thermal aftertreatment in combination with the Further processing of the internally oxidized material takes place. 10. The method according to claims 1 to 9, characterized in jge, that a raw material with strong internal tensions is used. 11. The method according to claims 1 to 10, characterized gejiennzeichnjiJL, that a powder is used as the starting material, which is produced by mechanical grinding of a compact alloy body was produced. ] £. Method according to the first to 11th, characterized in that a platinum-zirconium alloy with 0.1 to 5 % ^{zirconium, preferably 0.5 Ms 2 L} %, is used as the starting alloy. - 15 - 10983 1/1214 BAÖ ÖftfGINAl. 13. The method according to claims 1 to 11, since ge indicates that an alloy atis platinum with 1 to kO # rhodium and 0.1 to 5 ^c / o zirconium is used. 14. The method according to claims 1 to 11, characterized in that an alloy of platinum with 1 to 49 # palladium and 0.1 to 5 ^c / o zirconium is used EKENN g z eichnet. Prankfurt / Main, January 22, 1970
Schn / Bi 109831 / 12U Blank page