JPH01312055A - Wear-resistant coating material - Google Patents

Abstract

PURPOSE:To obtain a wear-resistant coating material excellent in wear resistance, capable of joining to inexpensive base materials, and free from cracking by specifying the ratio of CrB content to the content of Ni-base or Fe-base self-fluxing alloy. CONSTITUTION:This wear-resistant coating material has a composition consisting of 30-70vol.% CrB and the balance Ni-base and/or Fe-base self-fluxing alloy and also has wear resistance equal to that of WC-Ni-base sintered hard alloy. Further, the above coating material can be joined firmly to inexpensive base materials, such as carbon steel. Moreover, since this material has relatively high linear expansion coefficient of about 12.1X10<-6>/ deg.C, it is practically free from cracking due to thermal stress even if applied to mase materials with complicated shapes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to wear-resistant coating materials for use on mechanical parts.

[Conventional technology and its issues]

Conventionally, the coating layer has been formed by thermal spraying a wear-resistant material or by using a slurry of wear-resistant metal powder and ceramics.
-(r) Many attempts have been made, such as a method of alternately laminating layers and then sintering, but all of them have had performance or manufacturing problems, and none of them can be said to be sufficient. In Japanese Patent Application No. 196362, carbide or boride powder and an organic binder are kneaded and coated on a base material, and after machining the coated layer, the organic binder in the coated layer is removed in a sintering furnace. A method for coating wear-resistant materials was proposed in which the metal binder was removed by heating and the molten metal binder was infiltrated into the coating layer and bonded to the base material.

By the way, in this coating layer, WC as a carbide and N1 as a metal binder were mainly used, but since the linear expansion coefficient of WC particles in the coating layer, which is a WC-Ni-based alloy, is as small as 6.2X10/℃, the linear expansion of the entire coating layer is Expansion rate is 8~9X107℃
It was small. Therefore, the base material is also made of 5US, which has a small coefficient of linear expansion.
It was only possible to directly coat 420J2 and high-speed tool steel.

Additionally, complex shapes tend to cause cracks in the coating layer due to thermal stress. Therefore, when coating an inexpensive base material (for example, carbon steel with a linear expansion coefficient of 12 to 1.3 x 107°C), it is necessary to adjust the linear expansion coefficient by reducing the amount of WC in the coating layer. As a result, wear resistance decreased and sufficient performance could not be obtained.

[Purpose of the invention]

In the present invention, the wear-resistant coating material has wear resistance comparable to that of conventional wear-resistant materials such as cemented carbide and WC-Ni-based alloys,
To obtain a wear-resistant coating material that can be firmly bonded to an inexpensive base material (carbon steel, etc.) and that is resistant to cracking even in complex shapes.

[Means to solve the problem]

In the present invention, chromium boride is kneaded with an organic binder to coat the base material, and after machining the coating layer, the organic binder is heated and removed in a sintering furnace, and the molten metal binder is added to the chromium boride layer. and bond to the base material.

〔Example〕

Examples will be described below.

In the present invention, an acrylic resin was used as an organic binder, methyl ethyl ketone was used as an organic solvent, and Ni-based self-soluble alloy particles were used as a metal binder. Average particle size 50μm
A slurry was prepared by mixing 100 parts by weight of the following chromium boride particles, 5 parts by weight of acrylic resin 'kO, and 10 parts by weight of methi-ethyl-ketone.

The screw material of the plastic processing machine used in this example is SCM435, and the screw is processed in advance to a dimension on the negative side of the finished dimension. The previously kneaded slurry is then coated onto the screw surface using a full spray device. This coated molded body is turned on a lathe until the thickness of the coating layer is about 1 mm.

Next, Ni-based self-fusing alloy particles (component B: 2.30, Si: 4.50, Fe:
<1.0°C: 0.15, Bal: Ni, 5% of other materials) Place it in the crucible, hold the screw in an upright position in the same crucible, store it in the sintering furnace, and perform the sintering process. Let's do it. The sintering conditions are a vacuum degree of 1×10 to I×1O−1.
torr, sintering temperature 0-400℃ (50℃/■1), 4
00~1100℃(5"C/min), 1100℃(
Hold for 30 minutes) → Furnace cooling.

After coating, the chromium boride particles are fixed to the screw surface via the acrylic resin by this method, but when the acrylic resin evaporates and decomposes during temperature rise, the chromium boride particles are fixed to the screw surface only by the adhesive force of the chromium boride particles. ICNiC during sintering
Penetrates into the Ni-based soluble alloy layer to form a wear-resistant material,
and diffusion bonded to the base material. The coefficient of linear expansion of wear-resistant material is 1
．． 2. At I x 10-6/°C, SCM435 12.
The temperature is 7×107°C.

Therefore, there was little thermal stress due to the difference in linear expansion, and a good coating layer was obtained without cracks occurring on the screw surface. According to this method, the volume fraction of chromium boride was 45%. The hardness of the coating layer was distributed in the range of T-TV 700 to 1000, and the hardness of the base material was HRCIO.

FIG. 1 shows a microscopic photograph of the metallographic structure of the screw surface treated by the above method. ] is the square IJ x-base metal, and the base metal 1
A wear-resistant coating layer 2 is well bonded thereon.

FIG. 2 shows the relationship between specific wear amount and friction speed, and shows comparable results when compared with conventional WC-Ni-based alloys.

The wear test was performed using the Okoshi type abrasion tester on the mating material 5KI) 11
, using quenched hardness HR, c58e, final load 18.9
This is under the conditions of Kp and friction distance of 600 m.

Further, FIG. 3 shows the relationship between the specific wear amount and the volume fraction of chromium boride at a friction speed of 3 m/sec. According to this, good results were obtained when the volume fraction of chromium boride was 30% or more. Further, the maximum volume fraction of chromium boride is 70%.

〔Effect of the invention〕

As detailed above, since the coefficient of linear expansion of the wear-resistant coating material according to the present invention is 11 to 13 Coating layers with equivalent abrasion resistance can be combined. Furthermore, since there is little thermal stress, it is possible to coat even complex shapes.

[Brief explanation of the drawings] Figure 1 shows a micrograph (50x magnification) of the metallographic structure of the screw surface, and Figure 2 shows the relationship between specific wear amount and friction speed of the example and conventional WC-Ni-based alloys. FIG. 3 is a diagram showing the relationship between the specific wear amount and the volume ratio of chromium boride in Examples. 1: Screw material

Claims (1)

[Claims] The volume ratio of chromium boride is 30 to 70%, the remainder is Ni group,
A wear-resistant coating material comprising at least one type of Fe-based self-fusing alloy.