DE3031583C2 - Use of a powder mixture as plasma spray powder - Google Patents

Description

as plasma spray powder.

2. Use according to claim 1, characterized in that that the powder mixture consists of

Molybdenum powder

Iron powder

Silicon powder

Manganese powder

Carbon powder

organic binder

10.0-21.0% by weight
71.1-87.6% by weight
0.4-6.0% by weight
0-0.4% by weight
0-4.0% by weight
0-2.5% by weight

as plasma spray powder.

3. Use according to claim 1, characterized in that the molybdenum component of the powder mixture Molybdenum or a ferromolybdenum alloy, silicon or a silicon component Ferrosilicon alloy and, as the iron component, cast iron is used for the purpose according to claim 1.

4. Use according to one of claims 1 to 3, characterized in that the powder mixture ^{contains carbon powder in an amount of 0 to 3.5 wt. 1} ™, for the purpose according to claim 1.

5. Use of a powder mixture that has a particle size of at least 95% less than 0.088 mm, consisting of

Molybdenum powder

Iron powder

Silicon powder

Manganese powder

Carbon powder

10.0-25% by weight
70.0-87.6% by weight
0.4-6.0% by weight
0-2.4% by weight
0-4.0% by weight

organic binder 0-2.5% by weight

as plasma spray powder.

6. Use according to one of claims 1 to 5 for plasma spraying coatings on iron substrates, in particular for producing bearing surfaces on piston rings or crown seals τη internal combustion engines.

The invention relates to the use of a powder mixture afc plasma spray powder, especially for the production of bearing surfaces with high wear and tear Abrasion resistance using the plasma spray process. The powder mixture can in particular for producing bearing surfaces on piston rings or crown seals in internal combustion engines, z. B. diesel or gasoline engines can be used.

An alloy coating meets on a piston ring or crown seal in a rotary engine on conditions that are not usual for other bearing surfaces. Other storage areas, e.g. B. Main crankshaft bearing surfaces and crankpin bearing surfaces, are of a fairly uniform temperature all in one Exposed to an oil bath while their contact surface experiences different pressures

On the other hand, a piston ring bearing surface must inter alia. gro-Be Temperature fluctuations, large pressure fluctuations, contact with reactive chemical combustion products, minimal lubrication compared to crankshaft bearings, contact with a Withstand foreign particles, etc. Mixtures of powders that are suitable for a use case are therefore not necessarily usable in a different environment. The piston ring is a prominent one Example. A material that is very successful however, the numerous conditions prevailing for a piston ring in an internal combustion engine are met often the conditions from that in a different environment than in an internal combustion engine somewhere appear.

There have been complicated coatings as bearing surfaces heretofore used from hard metals (US-PS 35 39 192, 36 90 686, 37 25 017, 38 14 447) to high-melting metal oxides (US-PS 36 97 091 and

37 94 334) were sufficient. Each of these coatings has its special advantage in a certain environment, either in terms of manufacture or end use. A particularly suitable material on the Molybdenum base is described in US-PS 36 90 686 and is currently used on piston rings for Internal combustion engines used Its main problem is that of economy since the price of Molybdenum has increased by as much as 20% in the past three years as a result, the cost of that is considered to be Powder used as starting material is very high. About half of the material applied by plasma spraying is abraded in the completion of coated piston rings according to US-PS 36 90 686 and although part of it is recovered from the grinding liquor formed, the cost difference is large. It there is therefore a need for a cheaper replacement

for the expensive molybdenum-rich coatings.

Bearing surfaces made of an alloy of molybdenum with a larger amount of iron, obtained by plasma spraying are applied, are z. B. from US-PS

38 19 384 known in the case of a powder containing 50 to 75% molybdenum and 50 to 25% iron, SÄ * suitable for

Coating the surfaces of piston rings described is. The US-PS 39 91 240 teaches the production of bearing surfaces from a by flame spraying applied powder containing cast iron, molybdenum and boron. DE-OS 24 56 238 also describes a composition of a powder containing iron, molybdenum and boron.

Alloy systems containing iron, molybdenum and silicon are old and there is one in such systems relatively wide silicon range known. The US-PS 23 83 969 describes a permanent magnet, containing 70% iron, 17% molybdenum and 0.1% silicon. The US-PS 36 55 365 describes a tool alloy from 20 to 48% iron, 25 to 50% cobalt, 10 to 40% molybdenum, 0.5 to 4% carbon and a smaller one Amount of silicon. The alloy is formed by hot work hardening three alloy powders. the US-PS 38 56 478 describes an alloy for valve

3 4

seats made of 10 to 12% molybdenum, 88 to 90% iron and gung), can be used if only the egg

0.05 to 20% silicon. analysis of the finished powder within the

From US-PS 37 23 092 fine alloys are specified composition range is standing

known for powder metallurgical purposes, which can optionally contain up to about 4 parts of manganese

40% molybdenum, up to 1% silicon, up to 15% manganese, 5 100 parts molybdenum and up to about 25 parts organic

Up to 2% carbon and possibly other metals and other materials per 100 parts of molybdenum may be present.

May contain non-metals. When this powder mixture for plasma spraying on

Slightly higher silicon concentrations are used in the iron substrate and the one applied in this way

US-PS 21 24 877 for a hard tool alloy coating with a fine silicon carbide (cf.

wrote. The molybdenum concentration is 4.5 to 10 grinding wheel to a smooth, fine final state.

10%, silicon 0.2 to 1.25%, the remainder iron. The property grinding is, you get an extremely satisfactory-

carbon, sulfur, phosphorus and manganese on the bearing surface, which is particularly useful for

is also mentioned Other publications that use charge in an internal combustion engine as a bearing

Alloys with an intermediate silicon concentrate surface for piston rings or crown seals

Describe functions are e.g. B. the US-PS 22 19 462 and 15 is suitable

23 54 147. As already said, are in compound

Higher silicon concentrations in alloys are powders, in contrast to powder mixtures, binders the US-PS 34 28 442 described. A common phenolic varnish can serve as a binder. Settlement contains a relatively small amount. Other examples of suitable organic binders are Molybdenum, i.e. 0.0 to 5.0%. The US-PS 31 61 948 BE 20 known, modified with epoxy or oil alkyd paints, writes a low melting composition, drying oils, e.g. B. linseed oil varnish, tung oil, natural Iron and molybdenum together with silicon in one rather or synthetic rubber as a solution in one Amount of 5 to 25% contains US Pat. No. 2,289,365 solvents or as latex, etc., organic resins describes a phosphorus-silicon-iron alloy of various types which are solvent-ver- molybdenum may contain in amounts up to 35% by weight. 25 vaporization or by chemical or by heat from phosphorus / silicon are dry to a maximum of hardening or hardening, can be used who -26% present, with the phosphorus 2 to 13% and the den. The type of organic binder is immaterial, Silicon can be 6 to 22%. The rest is iron. as long as it hardens in some way to make im DE-PS 2433 814 also describes a summary of the entire powder to be sprayed composition of iron, molybdenum and silicon with 45% 30 a predetermined analysis of the unalloyed state or less iron. to preserve. The Bhider will definitely be in the

No known publication describes the plasma flame destroyed and does not form part of the

Use of a powder mixture to produce a ten alloy.

Bearing surface by plasma spraying, the powder The following examples explain typical inventions

mixed 70 to 87.6% iron, 10 to 15% molybdenum, 35 powder compositions which can be used according to the invention,

0.4 to 6% silicon, 0 to 4% carbon and an organic which the hard alloy surfaces from with iron

cal binder in an amount of 0 to 2.5%, and silicon result in expanded molybdenum,
these ingredients totaling 100%.

According to the invention, such a powder mixture is used as

Plasma spray powder used. A comparatively 40 example ί
small amount of expensive molybdenum is used in
Combination with a mixture of iron and one

small amount of silicon, optionally together with a typical extender composition is that

small amount of carbon, used it was like this:
found that for a coating of a piston ring 45

or a crown seal iron together with egg iron powder (< 0.088 mm) 97%

A small amount of silicon as a cheap extender for silicon powder (< 0.088 mm) 1%

the expensive molybdenum can be used without carbon powder (<0.088 mm) 2%
the properties of the coatings with high molybdenum contents are significantly impaired. 50

Briefly stated, the invention consists of the example 2
application of a mixture of molybdenum powder, expanded with one mainly of iron powder and

a small amount of silicon powder. Another extender composition is the following

Extender, in the form of a plasma spray powder. The extender 55:
can be used as a mixture or as a spray powder

compound powder using an or- iron powder (< 0.088 mm) 98.5%

Ganic binders are incorporated. Silicon powder (<0.088 mm) 1.5%

The extender mixture consists of 98.5 bis

99.5% by weight iron powder, the remainder silicon powder. This 60 B '' I 3
Extender can optionally contain carbon up to ice
contain four parts per hundred of the iron / silicon extender. Another extender composition is to mix 790 to 900 parts by weight of the extender with the following:
by means of 100 parts of molybdenum or, as stated above, 65

stretched by a binder. Master alloys of iron iron powder (< 0.088 mm) 96%

and molybdenum, which contain 50 to 75% molybdenum, and silicon powder (< 0.088 mm) 0.5%

otherwise consist of iron (traces of impurities - carbon powder (< 0.088 mm) 3.5%

5 6

Example 4 Piston ring or a crown seal has the fol

gende composition:

Another extender composition that still

Contains manganese is the following: Molybdenum powder (< 0.088 mm) 14.3%

5 Extenders from Example 3 85.7%

Iron powder (<0.088 mm) 94.2%

Silicon powder (<0.088 mm) 1.0% Example 10

Manganese powder (<0.088 mm) 2.4%

Carbon powder (<0.088 mm) 2.4% Another plasma that can be used according to the invention

: 10 spray powder for application on a cast iron

Example 5 Piston ring or a crown seal has the fol

gende composition:

A preferred extender composition is

the following: molybdenum powder (<0.088 mm) 143%

15 Extenders from Example 4 85.7%

Iron powder (<0.088 mm) 95.0%

Silicon powder (<0.088 min) 1.0% Example 11

Carbon powder (<0.088 mm) 23%

Manganese powder (<0.088 mm) 0.2% The best known plasma spray powder for application

organic binder (<0.088 mm) 0.9% 20 on a cast iron piston ring or a crown seal has the following composition:
Many variations of the above extender compositions will occur to those skilled in the art of molybdenum powder (<0.088 now *) 15%
Even these extenders are diluted with molybdenum powder from Example 5
(<0.088 mm) in known mixing devices and 25 (<0.088 mm *) 85Vo
according to known methods to such a uniform

Mix the powders mixed as possible Though the *) At least 20% <0.044mm.
Particle size of the powder understood as <0.088 mm

⁽ stated, this means that at least 95% of Example 12

of the powder through a standard sieve with a clear 30

Mesh size of 0.088 mm go through, while another plasma which can be used according to the invention

expediently should be at least 20% <0.044 mm. Spray powder for application to cast iron under Bi- ^E The powder should be free of foreign matter. tion of a bearing surface after grinding has the

% following composition:

k examples 35

h molybdenum powder (<0.088 mm) 25%

* A typical example of an extender according to the invention from Example 5 75%

reversible plasma spray powder for application on a

A cast iron piston ring or a crown seal - example 13

- 'tung has the following composition: 40

Another plasma molybdenum powder (<0.088 mm) 10% spray powder that can be used according to the invention for application to cast iron with BiI extender from Example 1 90% formation of a bearing surface after grinding has the following composition:
^! B is ρ ie 1 7 45

Molybdenum powder (<0.088 mm) 10.0%

Another plasma extender that can be used according to the invention from Example 5 90.0%

Injection powder for application to a cast iron

The following example 14 has a piston ring or a crown seal

Average composition: 50

Another plasma molybdenum powder (< 0.088 mm) 23.8% spray powder for application on cast iron with BiI extender of Example 1 76.2% of a bearing surface after grinding has the

the following composition:
Example 8 55

Molybdenum pu] v2r (<0.088 mm) 16.5%

Another plasma extender that can be used according to the invention from Example 5 83.5%

Injection powder for application to a cast iron

Piston ring or a crown seal has the following - When using a tie it can be assumed

de composition: 60 will be that the predominant component, the egg

sen, is provided with a coating that is a binder

Molybdenum powder (<0.088 mm) 21% and the molybdenum and silicon in unalloyed or

Extender of Example 2 contains 79% prealloyed state.

In the above compositions can

If there are other constituents present in quantities which the

Alloys on the bearing surfaces are not unfavorable

Influencing another plasma that can be used according to the invention. Such components are found as injection powder for Aufbi'nlgung on a cast iron cleaning, z. B. phosphorus, arsenic, selenium etc. The SiIi-

molybdenum 10 to 25% by weight iron 70.0 to 87.6% by weight omnium 0.4 to 6.0 wt.% manganese 0.0 to 0.4 wt% carbon 0.0 to 4.0 wt% organic binder 0.0 to 2.5 wt%

zium in the above compositions be wholly or partially replaced by sulfur.

The preferred plasma spray powders are characterized by an exceptionally high level Iron content in relation to molybdenum content for this type of application. The presence of silicon with or without carbon (preferably with) supports the wear resistance. In general it turns out that the weight ratio in the above examples of iron to molybdenum in the range of 9: 1 to 3.2: 1 and that iron and molybdenum together make up 90 to 99% by weight of the powder. Silicon is between 0.4 present up to 6% by weight of the powder.

The plasma spray powders of Examples 6-15 give a general analysis as follows:

Of course, the aforementioned powder elements are seldom in the pure state to a reasonable one Price available. As a result, you can use reagent-grade powders, but if you use their If you want to reduce costs, you can use commercially available powders with very satisfactory results the traces of normal contaminants, e.g. B. silicon, nickel, cobalt, chromium, aluminum, carbon etc, included.

The conditions for plasma spraying are those known to the person skilled in the art, as they are, for. B. in U.S. Patent 38 19 384 are described.

When applying a coating directly to a cast iron substrate, e.g. a compression ring Piston, the substrate is conveniently, although not essential, to a temperature of 93 to 232 ° C preheated.

45 50 55 60 65

Claims (1)

Patent claims: 1. Use of a powder mixture that has a particle size of at least 95% less than 0.088 mm consists of Molybdenum powder Iron powder Silicon powder Manganese powder Carbon powder organic binder 10.0-25% by weight
70.0-87.6% by weight
0.4-60.0% by weight
0-0.4 wt%
0-4.0% by weight
0-2% by weight