JPS6092444A - Nonmagnetic sintered hard alloy - Google Patents

Abstract

PURPOSE:To obtain the titled alloy having superior strength at high temp. and superior resistance to corrosion and oxidation by using a Ti-Ni alloy as a binder for the carbide, carbonitride or nitride of a IVa, Va or VIa group transition metal in the periodic table as a base material. CONSTITUTION:This nonmagnetic sintered hard alloy contains 0.5-40wt% Ti-Ni alloy contg. 7-20wt% Ti in one or more kinds of compounds selected among the carbides, carbonitrides and nitrides of the IVa, Va and VIa group transition metals in the periodic table. When the amount of Ti in the binding phase is <7%, the alloy shows magnetism, and when the amount is >20%, an abnormal phase is produced and exerts unfavorable influence on the strength of the alloy. When the amount of the Ti-Ni binding phase in the alloy is <0.5%, the sinterability and mechanical strength of the alloy are deteriorated, and when the amount is >40%, the hardness is remarkably reduced.

Description

[Detailed description of the invention] The present invention relates to a non-magnetic cemented carbide.

Currently, cemented carbide is used in a wide range of applications as a material with excellent mechanical properties such as hardness and strength.

However, the most widely used cemented carbide is tungsten carbide-based cemented carbide, which usually uses cobalt as a binder, but since cobalt is a ferromagnetic material, Hard metals also become ferromagnetic. Also,
Reducing the cobalt content to make a cemented carbide using cobalt as a binder non-magnetic is not only ineffective, but also reduces the mechanical strength of the cemented carbide as the amount of cobalt decreases. .

Therefore, if non-magnetism is required depending on the application of the cemented carbide, it is necessary to use nickel as a binder, reduce the amount of carbon in tungsten carbide than the theoretical value, melt tungsten into the nickel, and lower the Curie point. Attempts have been made to make the material non-magnetic, and to use a copper-nickel alloy as a binder phase.

However, the alloy obtained by the above method is not necessarily satisfactory in high temperature strength, corrosion resistance, or acid resistance.

The present invention was developed after repeated research in view of the above-mentioned problems, and it has been developed to improve the properties of cemented carbide, without sacrificing mechanical properties such as high-temperature strength (and excellent corrosion resistance or oxidation resistance). The purpose of this study is to provide a non-magnetic cemented carbide.

The present invention provides a ditanium-nickel alloy containing titanium in a weight ratio of 7 to 20% in one or more of carbides, carbonitrides, and nitrides made of transition metals in group 48.58.5a of the periodic table. It is a non-magnetic cemented carbide containing 0.5 to 4096.

Below, the reason for doing as described in ``1'' will be explained.

As is well known, titanium has excellent corrosion resistance and has a higher melting point than iron group metals, so a cemented carbide containing titanium has excellent corrosion resistance and also has an increased high temperature strength by 1. In terms of oxidation resistance, when titanium is present in the alloy, titanium oxide is formed on the surface of the alloy, delaying the progress of oxidation into the interior of the alloy, and as a result, the oxidation resistance of the entire alloy is improved.

Further, it is presumed that the reason why the alloy becomes non-magnetic is due to the following reasons. In other words, as shown in the original phase diagram of Nickel-Titanium in Figure 1, as the amount of titanium increases, the Curie point drops (magnetic transformation curve A) L, and when this exceeds 7% by weight, it becomes non-magnetic at room temperature. . Further, a part of the added titanium absorbs free carbon contained in the raw material tungsten and becomes titanium carbide. Therefore, the produced titanium carbide plays the role of a hard material.

However, if the amount of titanium in the binder phase is less than 7%, the alloy will exhibit magnetism, and if it exceeds 209 V, an abnormal phase will occur, which will adversely affect the strength of the alloy. For these reasons, the amount of titanium in the binder phase must be within the range of 7 to 20%. Note that titanium may be added by any method such as titanium powder or titanium hydride powder.

Furthermore, if the proportion of the titanium-nickel binder phase in the alloy is less than 0.5% by weight, the sinterability of the alloy will deteriorate and the mechanical strength of the alloy will deteriorate.
If the binder phase in the alloy exceeds 40%, the hardness decreases significantly.

As described in 1., the present invention provides non-magnetization and improvement of mechanical properties such as high-temperature strength, corrosion resistance, and oxidation resistance by using a titanium-nickel alloy as a binder. Of course, 4 ; 1 , 5 ; 1 , 5 a other than tungsten carbide
Effects similar to those described in +iiJ can also be obtained when carbides, carbonitrides, and nitrides made of transition metals of the group A are used as base materials.

Examples will be described below.

Example 1 Total carbon ff 16.20%, average particle size 3-4μ tungsten carbide powder 83g, titanium powder 2g, nickel powder 1
A solvent was added to 5 g, mixed in a ball mill for about 48 hours, dried, press-molded, and then heated at 1400°C for 60 hours.
Vacuum sintered for minutes. This sintered alloy is non-magnetic, and the alloy structure contains tungsten carbide and titanium carbide as hard phases, and the binder phase is nickel, titanium, tungsten,
It was a good product, containing no harmful phases such as η phase or free carbon.

Also, transverse rupture strength is 240 kq/rtra, hardness is HR
As was 2.8.

Example 2 Hard carbide and Ni-T were prepared by the method shown in Example 1 above.
A sintered body of i was manufactured with the composition shown in Table 1.

Table 1 In Table 1 above, Samples 1 to 9 indicate the compositions of the alloys of the present invention, and Samples 7alQ and 11 have alloy compositions used for comparison with the alloys of the present invention. The results of measuring the physical properties and magnetism of these materials are shown in Table 2 below.

As is clear from Table 2, all of the alloys of the present invention have no magnetism and exhibit excellent values in terms of transverse rupture strength and hardness.

Therefore, all of the cemented carbides according to the present invention have excellent non-magnetic super alloys, although their magnetic properties change depending on the binder phase, and their characteristic values differ slightly depending on the nature of the carbide or the wettability of the carbide and the binder phase. It becomes a hard alloy.

As explained above, the alloy according to the present invention becomes a non-magnetic cemented carbide by incorporating a predetermined amount of titanium-nickel alloy into a base material such as tungsten carbide, and has excellent high-temperature strength, corrosion resistance, and oxidation resistance. It also shows excellent properties.

[Brief explanation of drawings]

FIG. 1 is a nickel-titanium binary phase diagram. A--Magnetic transformation curve patent applicant

Claims (1)

[Claims] (1) Contains one or more carbides, carbonitrides, and nitrides consisting of transition metals in groups 48, 5a, and 5a of the periodic table, and contains titanium in a weight ratio of 7 to 2096 A non-magnetic cemented carbide characterized by containing 0.5 to 40% of titanium-12-ykel alloy.