NL8003868A - METHOD OF MANUFACTURING TURBO SHOVELS OF TITAN OR A TITANIC CONTAINMENT WHICH HAVE A HARD SURFACE. - Google Patents

Description

VO 6J2

Iv-. -.

Subject: Process for manufacturing turbo blades of titanium or a titanium alloy5 which are provided with a hard surface.

The invention relates to a method of manufacturing turbo vanes of titanium or a titanium alloy.

To keep the surface of turbo blades of titanium or a titanium alloy intact, in particular as protection against aggressive media at high temperatures and against erosion, these parts are increasingly provided with a protective layer. For nickel or nickel alloy turbo blades it is known to use aliteration, plasma spraying or other coating methods, whereby a protective layer is applied to the surface of the turbo blade, which layer can also be applied in the form of a lacquer. The main object in these known processes is to obtain a sufficiently high adhesion of the protective layer to the soil material and a sufficient resistance to frictional corrosion (fretting) and a sufficient resistance to long-term vibrations.

The object of the invention is therefore to provide a method for keeping the surface of turbo blades of titanium or a titanium alloy intact, while at the same time obtaining a high resistance to corrosion and the greatest possible protection against frictional corrosion and all kinds of erosions.

20 According to the invention, this object is achieved by applying a thin hard diffusion zone to the surface by nitriding, drilling or charring, and then irradiating the blade with a hard powder +

In the method according to the invention, as usual, a corrosion-providing additional protective layer is not applied to the ground material, but a thin superficial layer of the ground material is nitrated, bored or capped by diffusion and thereby hardened. The resulting thin, hard diffusion zone is then subjected to surface improvement by sandblasting. The roughness peaks are thereby exposed to plastic deformation, so that the notch effect can be reduced. In addition, internal sand stresses are built up in the boundary layer during sandblasting, which lead to better resistance to long-term vibrations. Other advantages of the method according to the invention are that it is possible to choose the layer thickness such that an economical production can be obtained.

Preferably, the process temperature during nitriding and charring is between 750 and 950 ° C and during drilling the temperature is preferably 950 ° C.

8003868 -2-

The action time is from 15 minutes to 3 hours for nitriding in a bath of cyan salts, for up to 15 hours for nitriding with gas and for up to 30 hours for ionitrants.

The working time does not have to be as great for coal-firing and for drilling as for nitriding with gas or for ionitrating, so that a working time of 1 - 10 hours is sufficient.

Preferably Al 2 O 2 sand is used for sandblasting. It has been found that a particularly good surface quality is then obtained. Other hard powders are also useful.

10 8003868

Claims (3)

Method of manufacturing turbo vanes of titanium or a titanium alloy, characterized in that a thin hard diffusion zone is applied to the surface by nitriding, horising or charring, and then the blade is blasted with a hard powder. 2. Process according to claim 1, characterized in that the treatment temperature during nitriding ο- "coal" is between 750 and 950 ° C and during drilling is about 950 ° C. Process according to claim 1 or 2, characterized in that the treatment time lasts from 15 minutes to 3 hours in nitration in a salt bath, in up to 15 hours in nitration in gas, and in up to 30 hours in ionitration. 10 b. Process according to claim 1 or 2, characterized in that the treatment time for charcoal is 1-10 hours and for drilling 2-10 hours. -o-o-8003868