Coating processes – Spray coating utilizing flame or plasma heat – Continuous feed solid coating material
Reexamination Certificate
1999-09-28
2001-11-27
Bareford, Katherine A. (Department: 1762)
Coating processes
Spray coating utilizing flame or plasma heat
Continuous feed solid coating material
C427S451000, C427S452000, C427S456000, C219S121460, C219S121470, C219S076140, C219S146230, C219S146410
Reexamination Certificate
active
06322857
ABSTRACT:
The invention concerns a material in powder or wire form on a nickel basis for the production of a coating with a high level of resistance to corrosion and wear by means of a thermal coating process, for example by thermal spraying, plasma powder build-up welding or arc welding. The invention also concerns processes for applying such a material and the uses of such a coating.
The use of nickel-based alloys with additives of chromium and molybdenum to give protection from wear and corrosion has long been known and is successfully involved in many branches of industry, for the purposes of thermal spraying and welding.
Thus for example U.S. Pat. No. 4,325,994 describes a relatively large number of nickel-based alloys with additives such as chromium, molybdenum, boron, silicon and other components. U.S. Pat. No. 3,999,952 also discloses alloys in the alloying range of between 5 and 15% by weight of B; between 5 and 50% by weight of Cr; between 1 and 50% by weight of Mo; and between 20 and 96% by weight of Fe, which moreover may additionally contain between 1 and 50% of Ni.
If consideration is given to those two specifications — or DE-A-25 56 960 and DE-A-38 23 140 — then it is noted that they primarily discuss coating or producing sintered bodies. In regard to those previously known alloys attention is directed to their good resistance to corrosion.
With knowledge of that state of the art the inventor set himself the aim of more substantially improving alloy compositions of that kind and in particular enhancing their resistance to wear and corrosion beyond the previously known level.
That object is attained by the teachings of the present invention which sets forth advantageous configurations.
By virtue of the invention it was in fact possible to manufacture alloys and with same to produce coatings whose resistance to wear and corrosion goes far beyond those properties of known alloys. That is afforded in fact by the addition of copper in a given alloying range to the additive elements molybdenum, chromium, carbon, boron and silicon, more specifically in the following ranges (in each case in percent by weight):
C
0.005-1.0;
Cr
10.0-26.0;
Mo
8.0-20.0,
Fe
0.1-10.0,
Si
3.0-7.0;
B
1.0-4.0;
Cu
0.1-5.0;
Ni
Balance,
in particular:
C
0.01-0.5;
Cr
14.0-20.0;
Mo
10.0-18.0;
Fe
0.5-5.0;
Si
4.0-6.5;
B
1.5-3.5;
Cu
1.0-4.0;
Ni
Balance,
or:
C
0.05-0.3;
Cr
15.0-18.0;
Mo
12.0-16.0;
Fe
2.0-4.0;
Si
4.5-5.5;
B
2.0-3.0;
Cu
2.0-3.0;
Ni
Balance.
The coating material is preferably used in powder form and can then also be mixed with an Ni—B—Si—powder and/or an Ni—Cr—B—Si—powder.
The invention also embraces a process for applying a material according to the invention for the production of coatings with a high level of resistance to corrosion and wear on a workpiece by a thermal coating process, in which the coating material in powder form is alloyed and sprayed from the melt or however agglomerated from various alloyed and non-alloyed metal powders.
In addition it has been found desirable for the coating material to be used in the form of filling wire or alloyed and cast bar material.
The operation of applying the material according to the invention can be implemented by thermal spraying by means of a plasma powder build-up welding process, a flame spraying process with subsequent fusing-in, a flame spraying process — in particular a high-speed flame spraying process —, an arc two-wire spraying process or with an arc welding process.
Tests have shown that a coating produced in the described manner preferably permits the following situations of use:
as a high-temperature protective layer;
as an anti-corrosion layer;
as an anti-wear layer.
Those protective layers serve to give protection from wear and corrosion in the chemical industry or in the pharmaceutical industry, in the paper industry, in the glass industry or in the plastics-processing industry.
REFERENCES:
patent: 4325995 (1982-04-01), Tamura et al.
patent: 223 135 (1987-05-01), None
patent: 826780 (1960-01-01), None
Heath Gary Robert
Heimgartner Peter
Kretschmer Ingo
Bachman & LaPointe P.C.
Bareford Katherine A.
Castolin S.A.
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