DE2054919A1 - Exhaust nozzle for hot gases - Google Patents

Description

D ι ρ 1. -1 η g.

r, ι η η ι ■ Auj :: burg, November 6, 1970 Rudolf Bussehneier

Patent attorney priority: December 29 , 1969

Augsburg 31 · Rehlingenstrasse 8 ° ^S * ^{err β ί ch}

P.O. Box2ί2 Note No. A 12050/69

rosti-chcikkonio: M u a ι lic η No. 745 39

5o36 / 20 / Bu / Ma

Patent application

Metallwerk Plansee AG & Co.KG, A-66OO Reutte, Tyrol, Austria

Outlet nozzle for hot gases

It is already known as a material for nozzles from which hot gases flow, such as this for example in rocket propulsion it is the case to use molybdenum, tungsten or alloys of these metals. Because of their high melting points, these metals withstand the thermal attack of the hot gases if they have a reducing effect. EuUialten However, the gases contain a substantial amount of oxidizing components, so the nozzle will through very soon Formation of volatile molybdenum or tungsten oxides destroyed.

The invention creates a nozzle in which, taking advantage of the thermal resistance of Molybdenum and tungsten a higher resistance to oxidizing gases is achieved. The invention relates to an outlet nozzle for hot gases, especially for Rocket propulsion or the like. According to the invention, the nozzle consists at least on the one exposed to the attack of the hot gases Part of its surface consists of a composite pot made of molybdenum, tungsten or alloys of these Metals and zirconium oxide. By adding zirconium oxide

10 * 830/1161 " ² "

ⁿ ORIGINAL

5636/20 / Bu / Ma - 2 - November 6, 1970

the destruction of the nozzle material is caused by oxidizing hot gases decisively delayed. The addition of zirconium oxide causes an increase at the same time the dimensional stability of the nozzle material.

An advantageous embodiment of the invention consists in that the part of the nozzle exposed to the attack of the hot gases contains 20 - Ö5, preferably hO - 75 »vol .-% molybdenum, tungsten or alloys of these metals. The greater the selected zirconium oxide content, the more resistant to oxidation the nozzle. However, one must take into account that the toughness of the nozzle material is somewhat reduced as the zirconium oxide content increases. When selecting the composition, a compromise will therefore generally be made between the requirements for high oxidation resistance and high toughness.

It is advisable to add stabilizing oxides such as calcium oxide or magnesium oxide in amounts of up to 10 % to the zirconium oxide phase.

The invention is explained in more detail using an exemplary embodiment. 50 VoI, -% finest molybdenum powder is mixed with finely powdered zirconia stabilized (relative to the Zirkonoxydphase) by the addition of 6 wt .-% calcium oxide, and pressed by the addition of conventional Preßzusätze into blanks, which correspond approximately to the required nozzle shape. The shaping of the blanks can of course also be carried out in other ways, for example by means of the slip casting process or by hydrostatic pressing. The shaped blanks are sintered in a reducing atmosphere (hydrogen) at 2000 ° C for three hours. The final nozzle shape can be worked out from the sintered blanks by grinding.

109830/1161

5636/20 / Bu / Ma - 3 - November 6, 1970

If the metallic component of the nozzle according to the invention is not formed from pure molybdenum or pure tungsten, it can be used in the form of alloy or mixed powders. Examples of such alloys are a known molybdenum alloy which contains about 0.5 % titanium and 0.07 % zirconium or a known tungsten alloy which contains 2 to 3 % nickel and 2 to 8 % copper or iron. In addition, alloys of molybdenum and tungsten with any desired composition, which still contain up to 10% rhenium, are also possible.

The metallic component of the nozzle should consist of at least 90% of the refractory metals tungsten, molybdenum and / or rhenium.

In general, it will not be necessary to manufacture the entire nozzle body from the composite material. The purpose of the invention is also achieved if the base body consists of a single unit Material, e.g. molybdenum, tungsten or alloys of these metals, and only on his, the surface exposed to hot gases is covered with the composite material. An easy way to achieve this consists in that on a corresponding molybdenum or tungsten base body by means of a plasma pestle the desired surface layer is sprayed on will. Another way would be, for example, that the one to be formed from the composite material Layer is sintered.

- patent claims -

109830/1161

Claims (4)

5636/20 / Bu / Ma - k. - November 6, 1970 claims 1. Outlet nozzle for hot gases, especially for rocket engines Or the like., characterized in that the nozzle at least on the attack The part of the surface exposed to the hot gases is made of a composite material made of molybdenum, tungsten or Alloys of these metals and zirconium oxide are made. 2. Nozzle according to claim 1, characterized in that the exposed to the attack of the hot gases Part of the nozzle 20 - Ö5, preferably 40 - 75, Vol.-56 contains molybdenum, tungsten or alloys of these metals. 3. Nozzle according to claims 1 and 2, characterized in that at least 90 % of the metallic components are formed from the refractory metals tungsten, molybdenum and / or rhenium. 4. Nozzle according to claims 1 and 2, characterized in that the zirconium oxide phase of the composite material contains additives of stabilizing oxides, for example up to 10 % calcium oxide or magnesium oxide. 109830/1161