JPS6043912B2 - Hard coated sintered body - Google Patents

Description

[Detailed Description of the Invention] Conventionally, as wear-resistant materials and tool materials, steel materials such as high carbon tool steel, high carbon alloy tool steel, high speed tool steel, and WC-Oo have been used.
Sintered materials such as TiC-Ni type, TiC-Ni type cemented carbide, and cermet have been used.

However, the former is strong but has poor abrasion resistance, while the latter has excellent abrasion resistance but is brittle. Therefore, one possibility is to coat the former with a hard material.

However, as a sumo wrestler, it is difficult to machine the former into the desired dimensions and shape, and the yield is also low, making it expensive and unsuitable for mass production. Therefore, in the present invention, we considered manufacturing iron or iron alloy into desired dimensions and shapes using powder metallurgy. Here, the above-mentioned high carbon tool steel, high carbon alloy tool steel, and high speed tool steel have poor press formability and sinterability, and are difficult to put into practical use, so they cannot be used.

Therefore, as in the present invention, it is best to use iron or an iron alloy as the core, which has sufficient strength and has good press moldability and sinterability. Of course, it may be infiltrated after sintering. Iron or iron alloys that satisfy these conditions are extremely soft compared to wear-resistant materials and tool materials, and cannot withstand use even when coated with hard materials. Therefore, in the present invention, the iron or iron alloy sintered body is carburized, nitrided,
By applying a surface hardening treatment such as borening treatment or induction hardening, and then coating the material with a hard material, we succeeded in obtaining an inexpensive wear-resistant material and tool material that has both toughness and wear resistance. The coating method is chemical vapor deposition (CVD).
The hardened layer on the surface of the iron sintered body changes in quality due to high temperatures of around 000℃, so physical vapor deposition (PVD), which can be coated at low temperatures, is used.
) Ion plating method is recommended. The most suitable coating materials are carbides, nitrides, carbonitrides of group A metals, and solid solutions with their oxides, which have high hardness and excellent heat resistance. A small amount of ferrous metal may be added or multiple layers may be used.
The above hard coating material is expressed as M(CU, Nv, Oω)z, where M is a group metal (Ti, Zr, Hf), C, N
, O represent carbon, nitrogen, and oxygen, respectively, U, υ, and ω represent the atomic ratios of C, N, and O, respectively, and u+υ+ω=19U,
V9ω≧0, z indicates the stoichiometric ratio of the non-metal component to the metal component, and z≦1.

As for the manufacturing process, it goes without saying that machining such as grinding, cutting, coining, and sizing may be added after sintering and surface hardening treatment, or heat treatment may be added after coating.

Examples are shown below. Example Mainly sprayed iron powder, with 2wt% reduced steel powder and 0.8
Using a mixed powder of Wt% graphite powder, the density was 6.9V/d when molded with a mold pressing force of 5.8t/Clt.
A molded body was obtained.

When this was sintered at 1130° C. for 30 minutes in an RX gas atmosphere, a sintered body with a density of 6.8 y/d and a hardness of HRB 85 was obtained. This sintered body was made to have almost the same shape as the cemented carbide throw-away chip SNu432. Next, this sintered body was induction hardened to form a hardened layer. Note that no tempering was performed. Further, the black scale portion on the entire surface of this sintered body was removed by grinding.

Titanium heated and vaporized by an electron beam was ionized at an ionization voltage of +60 cm, and a substrate voltage of -0.3 KV was applied to this sintered body using a reactive ion blating apparatus shown in FIG. The gas atmosphere is nitrogen gas 3×10-4
When it was held for 1C@ at T0rr and then for 9 hours at 4 x 10-4 T0rr in an acetylene gas atmosphere,
A coating film having a TiN layer of 0.5 μm and a TiC layer of 4.5 μm was obtained.
The hardness of the surface hardened layer was HRA8O. Using this coated sintered body, a turning wear resistance test was conducted together with high speed steel (SKH57) of the same shape.

Work material SCM Next tool YNllR-44A is used, cutting speed is 307TL/Minl, depth of cut 27nm, feed 0.1?
When cut for 2 minutes under the conditions of /Rev, the blank wear of the coated sintered body of the present invention was 0.14T! ! It was small as n, but is it 0.25 for high speed steel? This greatly proves the superiority of the coated sintered body of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an in-on brating apparatus used to produce the sintered body of the present invention, and the numbers in the figure indicate the following parts, respectively. 1... Vacuum chamber, 2... Intake vibe, 3
...Board power supply, 4...Board, 5...
...Ionization power supply, 6...Ionization electrode, 7...
... Reactant gas introduction vibrator, 8... Evaporation source.

Claims (1)

[Claims] 1. There is a hardened layer on the surface of the sintered body mainly composed of iron, and a part or entire surface of the hardened layer is mainly made of M (Cu, Nυ,
Oω)z, where M represents a group IV-a metal (titanium, zirconium, hafnium), and C, N, and O represent carbon, nitrogen, and oxygen, respectively. u, υ, ω indicate the atomic ratio of C, N, O, respectively, and u+
A hard coating film is formed by the PVD method, where υ+ω=1, u, υ, ω≧0, z indicates the stoichiometric ratio of the non-metallic component to the metal component, and 0<z≦1. A hard-coated sintered body characterized by the following characteristics: