JPS58164785A - Wear resistant composite powder for spraying - Google Patents

Abstract

PURPOSE:To enhance the lubricity at high temp., by combining >=1 kinds among solid lubricating substance selected from MoS2, WS2, graphite and BN with >=1 kinds among wear resistant substance selected from metallic carbides and metallic nitrides which are melted under ordinary pressure. CONSTITUTION:The composition of wear resistant composite powder for spraying is composed of 0.1-20wt% of >=1 kinds among solid lubricating substance selected from MoS2, WS2, graphite and BN and the balance >=1 kind of wear resistant substance selected from metallic carbides and metallic nitrides which are melted under ordinary pressure. The metallic carbides include Cr carbide, W carbide and Mo carbide, and the metallic nitrides include CrN and TiN. Co, Ni, Fe, Mo, Cu, an Ni-Cr alloy or an Ni-Cr-Fe alloy may be used as the wear resistant substance.

Description

Detailed Description of the Invention The present invention relates to a powder material for thermal spraying that has both lubricity and wear resistance at high temperatures. The present invention relates to a wear-resistant thermal spray material powder having excellent high-temperature lubricity and containing the above as a solid lubricant and at least one metal carbide or metal nitride as a wear-resistant substance.

Sliding members used at high temperatures and wear-resistant members used in dry conditions often require both lubricity and wear resistance. As a means for obtaining excellent lubricity, solid lubricating oils such as molybdenum disulfide, disulfide, tungsten, graphite, and boron nitride are used, which are stable even at relatively high temperatures. In addition to selecting wear-resistant metal materials, surface treatments such as induction hardening and hard chrome plating are used to improve wear resistance.

By the way, in order to improve the wear resistance of sliding members, it has been conventionally known that wear-resistant materials such as carbides or nitrides and metals or
Co-spraying with alloys is often carried out. Also,
Regarding tungsten carbide, a mixed powder of tungsten carbide and cobalt is used as a sintering powder. However, thermal spray coatings made of these powders have wear resistance, but often lack the required lubricity, and on high-speed, high-load sliding parts or dry sliding parts where oil cannot be used, they often seize or cause damage to the mating material. This has caused problems such as material wear.

Therefore, attempts have been made to simultaneously mix solid lubricants into these thermal spray materials and spray them. However, molybdenum disulfide, tungsten disulfide, graphite, and boron nitride, which have good lubricity, hardly melt during either flame spraying or plasma spraying, and some of them decompose, so they are hardly contained in the sprayed coating. It cannot contribute to the lubrication performance because it scatters.

The present invention provides a powder material for thermal spraying that efficiently incorporates a solid lubricant, which cannot be thermally sprayed alone, into a thermal spray coating as described above.

That is, one aspect of the present invention basically consists of a solid lubricant powder of at least one of molybdenum disulfide, tungsten disulfide, graphite, and boron nitride, which have high lubricity, and a solid lubricant powder that has high hardness and wear resistance. At least one of the metal carbide or metal nitride wear-resistant material powders that has a
The object of the present invention is to provide a powder material for thermal spraying which is a composite of more than one species in an appropriate ratio.

Yet another invention provides a powder material for thermal spraying, which is a composite of the solid lubricating substance, the wear-resistant substance, and a metal or alloy.

When a simple mixed powder method of a solid lubricant and an anti-wear substance is thermally sprayed, each particle of the solid lubricant flies alone in the spray gas without melting, so it does not adhere to the material as a thermal spray coating. It almost never happens.

On the other hand, in the present invention, melting occurs during the thermal spraying process.
If the solid lubricant is pre-compounded with a molten material and then thermally sprayed, the solid lubricant will fly while being captured by the molten material.
It becomes possible to incorporate a considerable amount into the thermal spray coating. Therefore, it is possible to obtain a thermal spray coating that has both lubricity and wear resistance.

Furthermore, when a metal or metal alloy is used, the bonding strength between the sprayed coating and the base material is significantly improved, and the toughness of the sprayed coating itself is also improved.

Next, the present invention will be explained in detail.

In the present invention, substances that are stable at high temperatures and exhibit lubricity include fine powders of commonly used solid lubricants such as molybdenum disulfide, tungsten disulfide, graphite, and boron nitride. can be used.

The particle size of these fine powders is desirably 3'50 mesh or less in order to be captured by the molten wear-resistant material or metal. Molybdenum disulfide and carbon do not melt during the thermal spraying process □,
Since it flies in a powder state, it cannot be effectively sprayed alone. Furthermore, since tungsten disulfide and boron nitride decompose at the spraying temperature, they cannot be sprayed effectively alone.

On the other hand, carbides or nitrides that provide wear resistance must have a temperature difference of several hundred degrees or more between their melting point and boiling point, and examples of carbides include chromium carbide, tungsten carbide, molybdenum carbide, titanium carbide, Sealconium carbide, etc. can be used, and as the nitride, chromium nitride, titanium nitride, zirconium nitride, etc. can be used. Since these are melted during thermal spraying, they adhere well to the substrate.

In addition, metals or alloys that can be used include cobalt, nickel, iron, molybdenum, chrome A, S, nickel-chromium alloys, and nickel-chromium-iron alloys, depending on the structural requirements of the sliding member used. It can be selected as appropriate.

These compounding ratios are not particularly limited and can be selected based on the required usage conditions of the sliding member, but they can be selected to maintain solid lubricant performance and wear resistance, and to maintain the film. Preferably 0 solid lubricant to maintain toughness
．． 1 to 20% by weight, remaining wear-resistant material, and when metal or alloy is used, 0.1 to 20% by weight solid lubricant, 5 to 40% by weight metal or alloy, remaining solid lubricant is suitable. .

Next, in order to effectively incorporate a solid lubricant substance into a thermal spray coating, it is necessary to include or attach the solid lubricant substance in a fine state to the wear-resistant substance and/or metal phase. Therefore, it is essential to form a powder in the form of a composite.

The method for producing the composite powder includes adding one part each of the solid lubricant substance and the wear-resistant substance, and if necessary, a metal or alloy.
Secondary particles are made by selecting at least one species and blending these materials to form a composite powder using granulation methods such as sintering and crushing, spray drying granulation, transfer granulation, or coating methods such as plating. can be obtained. In the composite powder thus obtained, the lubricating substance always coexists with the wear-resistant substance or metal during the thermal spraying process and does not separate, so that the object of the present invention can be achieved.

Next, an example of manufacturing the thermal spray box composite powder according to the present invention and the characteristics of the film produced when thermal spraying is performed using this powder are as follows.
A comparison is shown with the case of using conventionally used powder.

Example 1 Molybdenum disulfide powder with a particle size of 10 microns or less and chrome carbide powder were blended at a weight ratio of 2:8, thoroughly stirred, and then sprayed and granulated using polyvinyl alcohol as a binder. The obtained powder was heated at 180℃ for 1 hour.
After drying, the sieve was removed using a 200-mesh sieve to obtain a powder for thermal spraying.

On the other hand, as a conventional technique, molybdenum disulfide of 44 microns or less and chromium carbide powder were mixed at a weight ratio of 2:8 to prepare thermal spray powder for comparison.

The blasted size of both powders is 25
A thermal spray coating was prepared by plasma spraying onto a 40×4×SUS 304 plate. The plasma conditions were as shown in Table 1.

These thermal sprayed coatings in the table were finished to JIS standard 0.5S by machining and lapping, and then subjected to an abrasion test using an Okoshi type abrasion tester. The test conditions were as shown in Table 2. The results of the wear test are shown in Table 3.

Table 2 Table 3 As mentioned above, when compared with the coating using the mixed thermal spray material, the thermal spray coating using the composite powder according to the present invention showed no significant difference in the amount of wear, but no fusion phenomenon was observed, and it had good lubrication properties. It shows.

Example 2 Boron nitride, chromium carbide, and nickel-chromium alloy (all made of powder with a particle size of 15 microns or less)
80% Ni-2096Cr) at a weight ratio of 1:
After mixing at a ratio of 2 to 2 and forming into briquettes, sintering was performed at 1,000°C for 1 hour in an inert atmosphere, and the resulting sintered body was crushed and classified to obtain a composite powder with a mesh size of 350 to 200 meshes. .

On the other hand, powders of boron nitride, chromium oxide, and 2'7 Kelchrome alloy (80$Ni-20%Cr), all of which have particle sizes of 350 mesh to 200 mesh, were mixed in a weight ratio of 1:2. The mixture was thoroughly mixed at a ratio of 1 to 1, and was used as a thermal spray material for comparison.

A thermal spray coating was prepared using these powders in the same manner as in Example 1, except that grease was used as the lubricating oil.
A wear test was conducted under the same conditions. The results of the abrasion test are shown in Table 4.

Table 4 From these results, it can be seen that the thermal spray coating using the composite powder according to the present invention clearly has excellent wear characteristics.

Example 3 - Powders of tungsten disulfide, titanium nitride, and nickel, each having a particle size of 350 mesh or less, were mixed in a weight ratio of 1:6.
:3 was mixed in 1 and 1 parts, half of which was made into pre-nuts, sintered at 900'C for 1 hour, and then pulverized and classified to obtain a thermal spray powder with a mesh size of 35G or more and 200 mesh or less. The remaining half amount was simply mixed powder for thermal spraying. These thermal spray powders were plasma sprayed under the same conditions as in Example 1 to obtain thermal spray coatings. After the surfaces of these thermal sprayed coatings were ground, abrasion tests were conducted using an Odate abrasion tester under the conditions shown in Table 5.

Table 6 shows the specimen surface measurements immediately after the wear test was completed.

Table 5 Table 6 As is clear from the test piece surface temperature, when the composite powder of the present invention was used, the lubricating oil #-tX was lower than that of the simple mixed powder.
(It is possible to create a thermal sprayed coating that does not cause seizure even in the /- state and maintains good lubricity.

Patent applicant: Showa Denko Co., Ltd. Agent: Patent attorney Sei Kikuchi

Claims (2)

[Claims] (1) Molybdenum disulfide, tungsten disulfide, graphite,
and at least one solid lubricant substance selected from the group consisting of boron nitride, and at least one wear-resistant substance selected from the group consisting of metal carbides or metal nitrides that melt at normal pressure. A wear-resistant composite thermal spray powder characterized by being in the form of a composite. (2) Molybdenum disulfide, tungsten disulfide, graphite,
At least one solid lubricant selected from the group consisting of carbon dioxide and boron nitride, and at least one solid lubricant selected from the group consisting of metal carbides or metal nitrides that melt at normal pressure.
Comprised of at least one wear-resistant substance and a metal or alloy,
A wear-resistant composite thermal spray powder characterized by being in the form of a composite.