CN1014249B

CN1014249B - Embedding co-cementation of al and rare-earth alloy powders

Info

Publication number: CN1014249B
Application number: CN 88106961
Authority: CN
Inventors: 何业东; 朱日彰; 张文奇
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 1988-10-07
Filing date: 1988-10-07
Publication date: 1991-10-09
Also published as: CN1041789A

Abstract

The present invention relates to an embedding co-cementation method of Al and rare earth, in which parts are embedded in a cementing agent. The cementing agent is prepared from Al-rare earth alloy powder, Al-Fe-rare earth alloy powder, other alloy powder containing rare earth elements, alumina powder and chloride activators of different types. A metal part is processed by cementing and coating at a high temperature in an inert atmosphere, different activators are adopted according to the different contents of the rare earth in the cementing agent; therefore, the content of the rare earth in the cementing agent can be reduced, and an optimal Al-rare earth co-cementation coating can be obtained.

Description

Embedding co-cementation of Al and rare-earth alloy powders

Pack cementation aluminizing is to use a kind of very widely technology in the present industry, has that equipment is simple, cost is low, advantage such as easily produces by batch.But the oxide film that calorized coating at high temperature generates easily peels off, and the aluminium in the infiltration layer spreads in matrix comparatively fast, and its high temperature oxidation resistance is descended, and the anti-sulfuration and the hot corrosion resistance of calorized coating are also relatively poor.In order to improve the performance of aluminide coating, developed aluminium and other element confusion technology, as aluminium RE co-permeating, aluminium chromium ooze altogether, Al-Si co-infiltrating and aluminium titanium ooze etc. altogether.

The aluminium RE co-permeating can change the character that coatingsurface generates oxide film, improve the sticking power of oxide film, stop sulphur to spread effectively, thereby have good resistance to high temperature oxidation, anti-sulfuration and hot corrosion resistance, significantly improve the work-ing life of hot parts to matrix.

The aluminium RE co-permeating is to grow up on the basis of aluminising, adds rare earth element in original penetration enhancer, and metal parts is embedded in the penetration enhancer.

The penetration enhancer of embedding co-cementation of Al and rare-earth alloy powders must possess two conditions:

1. keep certain aluminium and rare earth activity when being coated with oozing; 2. the compound carrier and the gas phase rare earth compound carrier that should have gas phase aluminium in the penetration enhancer simultaneously.

So that the aluminium RE co-permeating patent of living is many patent claim is placed on the rare earth activity in the penetration enhancer,, NH is only arranged among their embodiment the not concrete definite requirement of promoting agent ₄Cl promoting agent.As the U.S.'s 3794511 patents, penetration enhancer middle-weight rare earths content is only said to add small amount of N H up to 55-73% prevailingly ₄Cl or volatile halogenated, the not amount of having.Day disclosure special permission communique, clear 56-87661, requiring penetration enhancer middle-weight rare earths content is 0.05-20%, with NH ₄Cl is a promoting agent, and content is 0.5%, and other promoting agent is not had concrete requirement.

The objective of the invention is to, reduce the content of rare earth in the penetration enhancer,, propose to select different promoting agent and content for content of rare earth different in the penetration enhancer simultaneously for obtaining best aluminium RE co-permeating coating.

The present invention uses respectively by Al rare earth alloy powder, iron Al rare earth alloy powder and other and contains the alloy powder of rare earth element and aluminum oxide powder and dissimilar muriate promoting agents is formed penetration enhancer.Metal parts is embedded in the penetration enhancer, under nonoxidizing atmosphere, under 800-1150 ℃ of high temperature, oozes and be coated with processing.

Adopt NH ₄Cl is a promoting agent, and oozing altogether with Al-y is example, in the reaction product liquid phase in the penetration enhancer with yCl ₃And yCl ₂Be main, the muriate of small amount of aluminum arranged, in gas phase with AlCl ₃AlCl ₂And AlCl ₁Be main, keep certain yCl simultaneously ₃And yCl ₂Dividing potential drop and its liquid equilibrium, based on the muriate of yttrium, the muriate of aluminium is secondary in the overall result penetration enhancer.YCl ₃And yCl ₂Generation consumed the y in the alloy powder, the activity of y is descended, first condition of oozing is altogether slackened.Therefore, with NH ₄When Cl was promoting agent, the content of rare earth in the penetration enhancer was higher, must be greater than the requirement that generates rare earth chloride.When penetration enhancer middle-weight rare earths content is higher,, adopt NH as＞1% ₄Cl ₁It is less to the activity influence of alloy powder middle-weight rare earths to make promoting agent.Improve the activity of aluminium in the FeAl rare earth powder, the NH that needs ₄Cl can reduce, and content is 0.1-0.5%, more helps the aluminium RE co-permeating.Content of rare earth＜1% o'clock adopts NaCl or KCl promoting agent, and content is 0.5-1%.Have only the small part rare earth to dissolve in NaCl or KCl, form rare earth chloride, still can keep certain rare earth chloride dividing potential drop balance with it in the gas phase, but be low than the previous case.When being promoting agent with NaCl or KCl, the activity of alloy powder middle-weight rare earths descends less, is applicable to the lower situation of penetration enhancer middle-weight rare earths content.The rare earth anhydrous chloride that with content is 0.5-1% is made promoting agent, rare earth in the alloy powder has only and dissolves in the rare earth anhydrous chloride on a small quantity and generate rare earth chloride at a low price, the consumption of alloy powder middle-weight rare earths is few, simultaneously can guarantee that gas phase has rare earth chloride dividing potential drop to greatest extent, with the rare earth anhydrous chloride is that promoting agent all is suitable for different content of rare earth in the penetration enhancer, but adopts rare earth chloride to be equivalent to improve the total amount of rare earth in the penetration enhancer as promoting agent.

Embodiment 1

Aluminium RE co-permeating sample adopts K38 nickel base superalloy (following identical), and its composition is as follows:

Aluminium rare earth pack cementation adopts 320 order FeAly(or Ce) its Chemical Composition of alloy powder is Fe39%, Al55%, y(or Ce) 6%, add 0.1%NH ₄Cl behind the uniform mixing imbeds sample.Under the argon gas that flows, 1000 ℃ ooze and are coated with 3 hours.Can obtain Ni ₂Al ₃It is main aluminium RE co-permeating coating.After handling, conventional diffusion annealing can change NiAl phase aluminium RE co-permeating coating into.

Embodiment 2

Aluminium rare earth pack cementation adopts 320 order Al-y(or Ce) alloy powder, contain y(or Ce) 8%, Al-y(or Ce in the penetration enhancer) alloy powder content 4%, NsCl0.75%, surplus is an aluminum oxide.Or Al-y(or Ce) alloy powder content 6%, KCl1%, surplus is an aluminum oxide.Behind the uniform mixing sample is imbedded, under the argon gas that flows, 1000 ℃ ooze and are coated with 3 hours, can obtain NiAl phase Al-y(or Ce) co-osmosized coating.

Embodiment 3

Al-y(or Ce in the penetration enhancer) alloy powder (the same) content 4%, yCl ₃Or CeCl ₃1%, surplus is an aluminum oxide, behind the uniform mixing sample is imbedded, and under the argon gas that flows, 1000 ℃ ooze and are coated with 3 hours, can obtain NiAl phase Al-y(or Ce) co-osmosized coating.

The aluminium RE co-permeating coating that above example obtains, through high temperature oxidation, thermal cyclic oxidation and thermal etching experiment prove that its performance all is better than calorized coating.

Elements C Cr Ni Co W Mo Al Ti Nb

Surplus the composition 0.15 16 8.5 2.6 1.7 3.4 3.2 0.8

Ta B Zr

1.7 0.01 0.1

Claims

1, a kind of embedding co-cementation of Al and rare-earth alloy powders method of part being imbedded penetration enhancer, form penetration enhancer by Al rare earth alloy powder or iron Al rare earth alloy powder and aluminum oxide powder and muriate activator, metal parts is embedded in the penetration enhancer, under inert atmosphere protection and 800-1150 ℃ of high temperature, ooze and be coated with processing, present method is characterised in that: described muriate activator adopts the anhydrous chloride of contained rare earth element in the diffusion agent alloy powder, and its content is 0.5-1%; Perhaps according to the difference of penetration enhancer middle-weight rare earths content,, use NH at this content of rare earth＞1% o'clock ₄Cl makes promoting agent, and content is 0.1-0.5%, and at content of rare earth＜1% o'clock, as promoting agent, content is 0.5-1% with NaCl or KCl.