DE1924092B1 - Process for the production of a high-temperature corrosion-resistant metallic coating on nickel or cobalt-based alloys - Google Patents

Description

The present invention relates to improved methods of processing various Alloys, especially the nickel and cobalt-based superalloys, around a corrosion-resistant coating on this with a long to maintain a long service life.

In the German patent application P 19 24 071.2-24 with the title: »Metallic coating for nickel and Cobalt-based alloys and use of the metallic coating for gas turbine machine parts «, Inventor: F. P. Talboom junior and J. Grafw all η er, a coating composition is described, which is intended for nickel and cobalt-based alloys and which are iron, chromium, aluminum and Contains yttrium or a rare earth metal, especially with the composition 20 to 50 percent by weight Chromium, 10 to 20 percent by weight aluminum, 0.03 to 2 percent by weight yttrium and / or rare Earth metal and the rest of iron.

The present invention was developed primarily to prevent oxidation, sulfidation, erosion and thermal shock resistance of gas turbine exhaust blades and fins, the Formed from nickel and cobalt based superalloys are to improve. Superalloys are to be understood as meaning such solid, high-temperature materials that their particular usefulness in their very busy neighborhood, as of Gas turbine engines. Representative of these alloys are those used in the industry with the following Composition use:

alloys are included. In particular, it comprises a cold-hot working sequence as part of a coating process, about the size and effect of any undesirable intergranular To reduce precipitate that can be formed in the deposition process.

The invention relates to a method for producing a high-temperature corrosion-resistant one metallic coating on nickel or cobalt-based alloys, characterized by the following process stages:

alloy

Composition (in percent by weight)

IN 100 10 Cr, 15 Co, 4.5 Ti, 5.5 Al, 3 Mo,

0.17 C, 0.75 V, 0.075 Zr, 0.015 B, balance Ni

MAR-M-200 9Cr, 10 Co, 2Ti, 5 Al, 12.5 W, 0.15 C, 1 Nb, 0.05 Zr, 0.015 B, balance Ni

WI 52 21 Cr, 1.75 Fe, 11W, 2 (Nb + Ta),

0.45 C, balance Co

MAR-M-302 21.5Cr, IFe, 10W, 9 Ta, 0.85 C, 0.25 Zr, balance Co

The characteristic of the typical superalloy consists on the basis of a solid nickel-chromium or Cobalt-chromium solution with additives of aluminum, titanium and / or resistant metals for solidification and carbon, boron and zirconium to provide improved creep rupture ductility.

It was found as described in the aforementioned German patent application P 19 24 071.2-24 it has been found that an alloy of the composition 20 to 50 percent by weight chromium, 10 to 20 percent by weight aluminum, 0.03 to 2 percent by weight yttrium and / or rare earth metal, remainder Iron causes long-term corrosion protection on the superalloys when applied as a coating has been. However, the effectiveness of the coating was found to be limited by the formation intergranular precipitation during the coating deposition cycle.

This invention describes an improved method of coating for various alloys give long-lasting corrosion resistance, with nickel and cobalt-based super-

a) Diffusion coating of the carrier material with an alloy of 20 to 50 ° / "chromium, 10 to 20% aluminum, 0.03 to 2% yttrium and / or

the rare earth elements, the rest iron;

b) cold working of the metallic coating;

c) Recrystallization annealing of the cold worked
Coating.

A special embodiment of the process is characterized by the following process stages:

a) Diffusion coating of the carrier material with a layer thickness of at least 7.62 x 10 ^-3 cm with an alloy of 25 to 29% chromium,

12 to 14% aluminum, 0.6 to 0.9% yttrium, the balance iron;

b) hammering the metallic coating;

c) Recrystallization annealing of the coating at 1038

or 1079 ⁰ C.
30th

Another embodiment of the invention is characterized in that diffusion coating by vapor deposition from a melt of the coating composition in a vacuum chamber is carried out.

In the preferred embodiment of the method, the coated articles are shot-like Hammering cold worked, especially by blasting with glass balls with the help of a blower.

In the more preferred embodiment of the method, articles made of nickel and Cobalt-based alloys have been molded with a composition that includes iron, chromium, aluminum and contains yttrium and / or rare earth metals,

coated and after coating heat treated, cold worked and heat treated to recrystallize to effect.

According to the present invention, the harmful excretion effect is eliminated by a

corresponding increase in the useful life of the coating through a compressive stress of the coating by cold working and subsequent heat treatment of the coating to to carry out a recrystallization. This treatment, preferably by shot hammering or by processing with glass balls, the precipitates break up into small particles, which are much more easily brought into solution by heat treatment and which in any case

are distributed more homogeneously within the coating. Accordingly, when the substrate is exposed to a corrosive attack on these along the separation line of the intergranular precipitate is avoided.

In the preferred method of coating the nickel and cobalt based turbine blades and Ribs must first carefully remove all dirt, grease and other substances from the surfaces to be coated

3 4

considerable foreign matter can be freed. The blades and ribs are then treated until they are prepared for a uniform coating with a layer by abrasive blasting and treated by vigorous washing with pure, thick water, excluding the diffusion zone. 7.62 x 10 ^-3 to 12.70 x 10 ^-3 cm. The diffusion zone for nickel-based superalloys is obtained by vacuum deposition with a melt flow of the coating alloy in a 2.54 x 10 ^-3 to 5.08 x 10 ^-3 cm for cobalt-based alloy vacuum chamber, which is set at 10 ~ ⁴ Torr or better gen 12.7 x 10 ~ ⁴ cm overall to 38.1 x 10 ~ ^4th
keep running. The Melt Used In the most preferred embodiment of the invention, moldings made of nickel and cobalt are preferably used with the following combination: io base superalloys in a vacuum chamber to

_. , _t to a layer thickness of 7.62 x 10 ^-3 to 12.7 x 10 ^-3 cm

Weight percent ..,, ... ' "',.

_T , ,,. ~. .-. , coated with a composition that

Carbon 0.02 maximum _{from 25 big 29 percent by weight carbon} , 12 to 14 genes

^ ° ψ ² ^ to 28 weight percent aluminum, 0.6 to 0.9 weight percent

Aluminum 12, S to 13.5 _{15 Yttnum UQd the rest consists of iron} . After this

", Γ ™? The moldings are coated to about 1038 ° C. ¹ λ μ ′ ι

£ ^h ° ^{sph <} f JOl ^max i ^ma for 4 hours in a non-oxidizing atmosphere

bcnweiei υ, υχ maximum _{heat j} . _{and cooled the} coated surfaces

bauerstoü 0.01 maximum _{are blasted with dry} glass balls and after

Nitrogen 0.005 maxima _{ao the radiation} n the coated parts with

Hydrogen 0.005 maximum of _{about 1079} o _{C for 4 hours oxvdiere} ^ _a ^ ligand

Other elements in total ... 0.5 maximum atmosphere kept.

Iron remainder ^ ⁶

Claims (1)

Patent claims: The parts are placed in the vacuum chamber at 954 ° C 25 during 5 minutes before the deposition started 1. Method of making a at high is, preheated and during the coating to temperatures corrosion-resistant metallic excess temperature held. The deposition time varies depending on nickel or cobalt-based alloys, something, but it is adjusted to the preferred characterized by the following coating thickness for the outside of Turbi- 30 speed levels: inner blades and ribs from 7.62 ^{· H) - 3} to 12.70 · _{a) Diffusion} coating of the carrier material blaze, excluding the diffusion zone to ER · _{Mt dner Le} ^ _he clothes from 20 to 50% chromium, are sufficient. Subsequent cooling to below 538 C _{w Us 2Q0} j aluminum, 0.03 to 2 " ₀ yttrium is in a non-oxidizing atmosphere through _and / or the rare earth metals, rest led to a cooling rate _sen 35 · egg · corresponds to cooling in air. This is followed by _b) cold working of the metallic coating; Covering the Tede to 1038 C in a vacuum _c) Recrystallization of the cold-worked be heated. The parts are coated at temperature
held for 4 hours; it becomes in non-oxidizing Atmosphere with a cooling rate 40 2. The method according to claim 1, characterized cooled, which corresponds to cooling in air. through the following process steps: The coated surfaces are then coated with _a ) diffusion coating of the carrier material ^ttO f? ^ S ^a ₃ ^S l ^Uge ^ nf ^S in 3 ' ^W £ \ Glass spheres _{with a layer thickness} e _of at least 7.62 with 17.78 · 10-3 _{bls 27j94} . ₁₀ _. _cm p _urchm e _SS e _r ver ₁₀ _ _{3 cm} ^ _{an alloy of 25} to 29% with an intensity corresponding to 15 N, 45 _{Ch 12 to 14 0 /} aluminum, 0.6 to 0.9% / ₀ speaks and where the radiation treatment in yttrium remainder iron Compliance with the precautions of _b) hammering the metallic coating; Aerospace material specifications AMS 2430 E _c) recrystallization annealing of the coating follows. 1038 or 1079 ⁰ C The 5 ° heat treatment that follows after the radiation consists in heating to 1079 ± 14 ° C in dry 3. Method according to claim 1 or 2, characterized Argon, dry hydrogen, or vacuum, characterized by diffusion coating through holding the temperature for 4 hours and cooling with vapor deposition from a melt of the superimposed Speed of cooling in air train composition in a vacuum chamber is equivalent to. 55 is carried out.