JPH0598383A - Hard alloy - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a hard alloy having excellent wear resistance, corrosion resistance, and toughness, high hardness, and no restriction in color tone. [Structure] Based on NbC, Ni, TaC, Mo,
With Cr, the alloy density is 7.0-10.0 g / cm ³ ,
A hard alloy having a Vickers hardness of 1000 kg / mm ² or more, preferably 35% by weight or more of NbC and Cr.
Is contained in an amount of 1.0 to 3.0% by weight. As a result, WC
It is lighter in weight and lower in cost than the conventional cemented carbide based on, and has a higher strength than cermets and ceramics and exhibits a color tone close to gold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard alloy suitable for use as a corrosion resistant decorative material, a sliding resistant material, a wear resistant material and the like.

[0002]

2. Description of the Related Art Conventionally, as a hard alloy used for a decorative material or the like, a cemented carbide having an excellent balance of wear resistance, corrosion resistance, toughness and color tone has been used. As an example,
WC-Co-Ni-Cr system, WC-TaC-Ni-Cr
System, TaC-Ni-Cr-Mo system cemented carbide, carbides and carbonitrides of Group IVa, Va and VIa of the Periodic Table are used as hard phases, Co and Ni are used as binder phases, and corrosion resistance is obtained. Therefore, there is a material to which Cr is added.

However, this kind of cemented carbide is WC or Ta.
Since it is based on C, the alloy density is 10.0 to 1
It is as high as 6.0 g / cm ^3, and there is a problem in terms of handleability, and moreover, it consumes a large amount of resources per unit volume, which causes an increase in cost. On the other hand, there is an environmental problem due to heavy use of heavy metals.

As a preventive measure, a cermet based on Ti or a ceramic based on Al oxide is used to reduce the weight of the product and reduce the production cost.

[0005]

However, in the conventional example using the above-mentioned conventional cermet and ceramics, since brittleness is smaller and strength is lower than that of cemented carbide, it is difficult to process such as brazing. In addition, there are drawbacks in that it is considerably limited in color tone, does not show a color close to gold, and is not suitable as a decorative material.

The present invention has been made to solve the above-mentioned conventional problems, and is excellent in wear resistance, corrosion resistance and toughness.
It is an object of the present invention to provide a hard alloy having high hardness and no color tone restriction.

[0007]

In view of the above, the present invention is mainly based on Nbc and has an alloy density of 7.0 to 1.
0.0g / cm ³ and Vickers hardness of 1,000
It was obtained as a result of investigations to obtain a hard alloy having a weight tone of kg / mm ² or more, which is particularly lightweight and has a high hardness and a color close to that of gold.

That is, the present invention is based on the group Va of the periodic table of elements,
It consists of one or more hard phases of VIa group carbides and a binder phase of an iron group metal and has an alloy density of 7.0 to 10.0 g.
/ Cm ³ , and the Vickers hardness is 1,000 kg / mm ² or more.

Further, the alloy composition is 35% by weight or more of NbC.
Is the main component and Cr is preferably contained in an amount of 1.0 to 3.0% by weight.

[0010]

According to the present invention, as described above, an alloy is obtained by using, as a hard phase, a carbide of a metal element of Group Va or VIa of the Periodic Table of the elements as a main component and an iron group metal such as Ni as a binder phase. The density is as low as 7.0 to 10.0 g / cm ³ and the Vickers hardness is 1,000 kg / mm or more to obtain a hard alloy that is particularly lightweight and easy to work.

The main component of the hard phase is, for example, N
bC is used, and 35% by weight or more is contained in the alloy to form the base of the hard alloy. If this NbC is used, coarse particles are easily formed during sintering. Therefore, TaC and Mo are added to suppress coarsening and improve the transverse rupture strength and hardness.

As the binder phase, Ni is used, for example, and is contained in the alloy in an amount of about 12.0% by weight.

Further, in order to improve the corrosion resistance of the alloy, C
r is added at a ratio of 1.0 to 3.0% by weight.

An example of the production of the hard alloy of the present invention will be described. The above raw material powders of NbC, Ni, TaC, Mo and Cr are wet mixed in a ball mill, granulated and dried,
After pressing at 1.3 T / cm ² , the molded product is pre-sintered under predetermined conditions, and then subjected to hot isostatic pressing (HIP) at a temperature lower than the liquidus appearance temperature, and thereafter. An alloy is obtained through polishing.

[0015]

EXAMPLES The present invention will now be described in detail with reference to examples.

Each of the compounds having the composition shown in Table 1 was wet mixed in a ball mill, and three kinds of raw material powders (Sample No. a,
b, c) were created.

[0017]

[Table 1]

After drying and granulating these three kinds of raw material powders, 1.
Press formed into 5 × 8 × 25 mm at 3T / cm ² , 1415
After pre-sintering at ℃ for about 1 hour, under argon gas atmosphere, high pressure of 1,000 kg / cm ² at 1350 ℃,
Hot isostatic pressing sintering (HIP) was performed for 1 hour, and polishing treatment was performed to obtain a hard alloy. Table 2 shows the results of investigation of wear resistance of this alloy. It can be seen that Sample No. a has a shorter cutting speed than Sample Nos. B and c. Here, the abrasion resistance test is a life time until steel cutting V _B = 0.3 mm,
Conditions are dry, V = 150 mm / min, f = 0.2 mm / rev
, D = 2.0 mm. (Hereafter, margin)

[0019]

[Table 2]

Further, Table 3 shows the results of investigation of the corrosion resistance of the obtained alloy. The conditions were erosion for 24 hours in a liquid adjusted to pH 3.5 and pH 4.5. As a result, in sample a, there was no corrosion at all, in b, some corrosion was observed, and in c, corrosion was observed. (Hereafter, margin)

[0021]

[Table 3]

Further, Table 4 shows the results of investigation of the heat resistance of the alloy as a material for rolling rolls. Sample No. a is other N
It can be seen that it has a longer life than o.b and c.

[0023]

[Table 4]

Further, the obtained alloy was polished and mirror-polished, and the color tone thereof was examined by a colorimeter. The results shown in Table 5 were obtained. As a result, it was confirmed that Sample No. a exhibited a color close to gold.

[0025]

[Table 5]

The hard alloy according to the present invention is most suitable as a decorative material because it has excellent corrosion resistance, and besides, can be widely used as a material for sliding resistant parts and a material for wear resistant parts. Incidentally, the corrosion resistance in some applications, toughness, to adjust the hardness ^{_{NbC x - (WC-Mo-}} Cr-TaC)
_{May be 1-x} organization.

[0027]

As described above, according to the present invention, unlike the conventional WC-Co-Ni-Cr cemented carbide, the alloy density is 7.0 to 10.0 g / cm ³ and the Vickers is. Since the hardness is 1000 kg / mm ² or more, the weight and cost are reduced, and the strength is higher than that of cermet or ceramic, and since there is no color tone restriction, it is easy to process such as brazing, and gold color It has the special effect of obtaining a color tone close to.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical indication C22C 38/18

Claims (2)

[Claims] 1. A hard alloy comprising a hard phase of one or more kinds of carbides of the group Va and VIa of the periodic table of elements and a binder phase of an iron group metal and having an alloy density of 7.0 to 10. 0
A hard alloy characterized by a Vickers hardness of 1,000 kg / mm ² or more in g / cm ³ . 2. The alloy composition according to claim 1, wherein the alloy composition is 35% by weight.
The above NbC is the main component, and Cr is 1.0 to 3.0.
A hard alloy characterized by containing by weight%.