Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Making composite or hollow article
Patent
1985-09-26
1987-07-21
Lechert, Jr., Stephen J.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Making composite or hollow article
75 05BA, 75 05C, 264 5, 264 12, 419 8, B22F 700
Patent
active
046817344
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of manufacture of a powdery material for thermal spraying (plasma or flame spraying), a material comprising a powder manufactured by this method as well as the employment of this material for the deposition by thermal spraying of a self-adhesive layer upon a substrate.
In the case of numerous alloys intended for being applied by thermal spraying onto a workpiece in order to form over its surface a protective coating, it proves necessary to apply previously over the substrate an intermediate layer in order to improve the adhesion between the substrate and the layer of protective coating.
Such intermediate layers intended for improving the adhesion to the substrate, are likewise obtained by thermal spraying of powdery materials which usually consist of Mo, NiAl, NiCrAl or NiAlMo. In particular in the case of the employment of nickel alloys containing additions of Al, Mo and Cr, one may obtain bond strengths higher than 20 N/mm.sup.2.
In addition attempts have been made to employ for the achievement of adhesive layers or self-adhesive layers of materials having a base of Fe, Co and Cu, instead of nickel alloys but it has, however, been impossible to obtain by means of these materials a sufficient adhesive strength with respect to a substrate.
The aim of the invention is to enable a material for thermal spraying to be obtained, which allows the production of a self-adhesive layer having a bond strenghth (as measured by standard tearing test by tension) higher than 20 N/mm.sup.2 upon a substrate, this material being free of nickel or containing only up to 10% of it by weight. The invention is aimed in particular at enabling the production of adhesive layers and of self-adhesive protective layers which exhibit a high resistance to corrosion by hot gases, more particularly in the presence of sulphur derivatives.
This result is obtained in accordance with the invention, thanks to the employment for the production of the layer by thermal spraying, of a thermal spraying material which contains a powder manufactured by the method in accordance with the invention. This method is characterized in that a molten alloy of composition by weight: chromium: 10 to 30%; aluminium: 1 to 25%; carbon: less than 0.5%; nickel: less than 10%; iron: the remainder; is subjected to atomization from the liquid state with a cooling speed of at least 400.degree. C./sec. and ranging up to 5000.degree. C./sec., so as to produce a powder having a grain size of from -150 to +27 microns, the specific surface of which is higher than 500 cm.sup.2 /g. The speed of cooling advantageously lies between 600.degree. and 5000.degree. C./sec. Equally advantageously the specific surface of the powder is higher than 750 cm.sup.2 /g. Preferably the alloy contains up to 2% by weight of one or more elements chosen from the following: Zr, Ce and Y. Equally preferably the alloy may contain from 0.5 to 5% by weight of molybdenum and/or 0.5 to 5% by weight of titanium or tantalum.
The material for thermal spraying advantageously contains in the form of a mixture, at least 20% by weight of the powder manufactured by the method in accordance with the invention and up to 80% by weight of at least one hard material as powder. This hard material is advantageously chosen form metallic oxides and carbides.
The material in accordance with the invention advantageously contains in the form of a mixture at least 20% by weight of the said powder and up to 80% by weight of a metallic powder chosen from the group consisting of the following elements: W, Mo, Ta, Ti and Cr. Equally advantageously the material in accordance with the invention may contain up to 80% by weight of an alloy having a base of iron, nickel or cobalt. By "alloy having a base of iron, nickel or cobalt" is to be understood, within the scope of the present invention, an alloy containing from 50 to 99% by weight of iron, nickel or cobalt and at least one other element and the composition of which lies respectively within the following limits (expressed in percent by weight):
REFERENCES:
patent: 4297135 (1981-10-01), Giessen et al.
patent: 4355057 (1982-10-01), Slaughter
patent: 4377375 (1983-03-01), Slaughter
patent: 4385929 (1983-05-01), Ichidate et al.
patent: 4420336 (1983-12-01), Klar et al.
patent: 4430115 (1984-02-01), Ray et al.
patent: 4437883 (1984-03-01), Kubo et al.
patent: 4540546 (1985-09-01), Giessen
Simm Wolfgang
Steine Hans-Theo
Castolin S.A.
Lechert Jr. Stephen J.
LandOfFree
Heat spraying material and manufacturing process thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat spraying material and manufacturing process thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat spraying material and manufacturing process thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-206260