CN112609116B

CN112609116B - Hard alloy for strengthening Co-Ni-based binder phase through Si and preparation method thereof

Info

Publication number: CN112609116B
Application number: CN202011372879.4A
Authority: CN
Inventors: 龙坚战; 汪巍; 伍文辉
Original assignee: Zhuzhou Cemented Carbide Group Co Ltd
Current assignee: Zhuzhou Cemented Carbide Group Co Ltd
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2021-11-30
Anticipated expiration: 2040-11-30
Also published as: CN112609116A

Abstract

The invention discloses a novel cemented carbide with a binder phase and a preparation method thereof, wherein the cemented carbide comprises, by mass, 10-15 wt% of cobalt, 10-15 wt% of nickel, 0.6-2.5 wt% of silicon carbide and the balance of tungsten carbide. The invention adopts Si-strengthened Co-Ni binding phase to strengthen the hard alloy, and the ordered strengthening phase is dispersed and distributed in the binding phase. Under the same conditions, compared with the existing Co-Ni binding phase hard alloy, the enhanced hard alloy taking Co-Ni-Si as the binding phase can realize the improvement of the bending strength at room temperature and high temperature by more than 20 percent; the process of the invention is simple and controllable, and is beneficial to realizing industrialization.

Description

Hard alloy for strengthening Co-Ni-based binder phase through Si and preparation method thereof

Technical Field

The invention belongs to the technical field of hard alloy, and particularly relates to a novel binder phase hard alloy and a preparation method thereof, in particular to a reinforced hard alloy which is prepared by using powder metallurgy technology and takes WC as a hard phase and Co-Ni-Si as a binder phase, and a preparation method thereof.

Background

WC-based cemented carbides are widely used as cutting tools, mining tools, wear-resistant parts, and the like because of their high strength, high hardness, high wear resistance, and high red hardness. It is well known that the wear resistance of conventional WC-Co cemented carbides depends mainly on the hardness of the alloy. The hardness and toughness of the traditional WC-Co hard alloy are opposite to those of the spear shield, namely, the hardness of the alloy is improved by sacrificing certain toughness as a price. Research shows that under the condition of equivalent alloy hardness and fracture toughness, the WC-Co hard alloy for strengthening the binding phase has better wear resistance compared with the traditional WC-Co hard alloy. For example, in the article "Novel reinforced binder phase ultra-coarse Hard alloy for mining tool" (English: Novel ultra-coarse binder phase grains with re-formed binder and construction) published by Konyashin et al, Vol.23 (International Journal of Refractory Metals and Hard Materials) pp.225 @, 232, 2005, ordered L12 structure grains Co3W of about-3 nm are precipitated in Co binder phase by a heat treatment method to reinforce the binder phase, so that the wear resistance of the alloy can be remarkably improved under the condition that the toughness of the alloy is not reduced, and the service life of the alloy tool is improved by 2-WC 3 times compared with the conventional ultra-coarse crystal Co Hard alloy. However, the method has extremely high requirements on carbon content, great control difficulty and complex process.

In addition, the addition of hard particles to cemented carbide also enhances the properties of the alloy by strengthening the binder phase to form particles. Such as nano-whisker silicon carbide, the particles have good strengthening effect on the Ni-based binding phase of WC-Ni hard alloy. The Effect of nanowhisker silicon carbide addition on hot pressed sintered WC-Ni based cemented carbide is mentioned in an article published by Ren et al, volume 36, 2013, International Refractory Metals and Hard Materials, p 294, 299, which is the Effect of nanowhisker silicon carbide addition on WC-Ni based cemented carbide, which improves some of the properties of the alloy. This method is directed only to Ni-based binder phases. When the content of the binder phase is low, the silicon carbide is only used as hard phase particles for strengthening and does not form solid solution or third-phase precipitation strengthening with the matrix of the binder phase, so that the strengthening effect is limited; and the silicon carbide in the alloy prepared by the method is easy to agglomerate in the microstructure structure.

Disclosure of Invention

The invention aims to provide a novel hard alloy which is strengthened by Si and has a Co-Ni-based binder phase and a preparation method thereof.

The hard alloy of the Si-reinforced Co-Ni-based binder phase comprises, by mass, 10-15 wt% of cobalt, 10-15 wt% of nickel, 0.6-2.5 wt% of silicon carbide and the balance of tungsten carbide.

The granularity of the silicon carbide is 0.6-3.0 um.

Preferably, the hard alloy with the Si-reinforced Co-Ni-based binder phase consists of, by mass, 13-15 wt% of cobalt, 13-15 wt% of nickel, 0.6-2.5 wt% of silicon carbide and the balance of tungsten carbide.

Further preferably, the cemented carbide with the Co — Ni-based binder phase strengthened by Si is composed of, by mass, 13 wt% of cobalt, 13 wt% of nickel, 0.6 wt% of silicon carbide, and the balance of tungsten carbide.

Further preferably, the cemented carbide with the Co — Ni-based binder phase strengthened by Si is composed of, by mass, 15 wt% of cobalt, 15 wt% of nickel, 1.5 wt% of silicon carbide, and the balance of tungsten carbide.

The preparation method of the hard alloy for strengthening the Co-Ni-based binder phase by the Si comprises the following steps:

firstly, carrying out pre-wet grinding on silicon carbide powder, then adding cobalt powder, nickel powder and tungsten carbide powder according to a ratio, and continuously carrying out wet grinding; after wet milling is finished, spray drying and compression molding are carried out to obtain a pressed blank; and (3) carrying out low-pressure liquid phase sintering on the pressed compact at a set temperature, and obtaining the novel cemented carbide after sintering.

The pre-wet grinding time is 6-12 h, the continuous wet grinding time is 18-36 h, the sintering temperature is set to be 1350-1450 ℃, the pressure at the sintering temperature is 0.6-1.0 MPa, and the sintering heat preservation time is 1-2 h.

The hard alloy with the Si-reinforced Co-Ni-based binder phase is applied to the preparation of high-temperature resistant die, roller and cutter materials.

The principle of the invention is as follows: the invention adds silicon element into Co-Ni binding phase hard alloy to separate out A3B (A represents Co and/Ni element, B represents Si element) ordered phase deposition, thereby strengthening the binding phase of the hard alloy, improving the strength and wear resistance of the alloy, keeping the strengthening function of the binding phase up to 800 ℃, and greatly improving the high-temperature bending strength performance of the alloy. The method for forming the A3B ordered phase is to add an intermediate compound silicon carbide in the wet grinding process, then decompose and diffuse the silicon carbide in the liquid phase sintering process to enter a Co-Ni binding phase to synthesize the A3B ordered phase precipitate in situ, thereby strengthening the precipitation of the binding phase.

Meanwhile, the hard alloy Co-Ni binder phase provided by the invention has a weight percentage content of 20-30%, belongs to a high binder phase content, and has a more obvious strengthening effect. In addition, because the hard alloy contains Co element, the compatibility of the binding phase and the silicon element is improved, the solid solution of the liquid phase binding phase relative to the silicon element is accelerated, and the solid solution amount of the binding phase relative to the silicon element is improved, so that the silicon carbide can be fully decomposed and dissolved into the binding phase. The problem that single Ni bonding is low in solid solution relative to silicon element is solved, and the conversion of silicon carbide from particle strengthening to A3B ordered phase precipitation strengthening is promoted.

The invention has the beneficial effects that: the invention adopts Si-strengthened Co-Ni binding phase to strengthen the hard alloy, and the ordered strengthening phase is dispersed and distributed in the binding phase. Under the same conditions, compared with the existing Co-Ni binding phase hard alloy, the enhanced hard alloy taking Co-Ni-Si as the binding phase can realize the improvement of the bending strength at room temperature and high temperature by more than 20 percent; the process of the invention is simple and controllable, and is beneficial to realizing industrialization.

Drawings

FIG. 1 the texture of cemented carbide prepared in example 1;

FIG. 2 is a comparison of the flexural strength at room temperature of the cemented carbide made in example 1 versus a conventional Co-Ni binder phase cemented carbide (comparative example 1).

FIG. 3 is a graph comparing the flexural strength at different high temperatures of the cemented carbide made in example 1 with that of a conventional Co-Ni binder phase cemented carbide (comparative example 1);

FIG. 4 the microstructure of the cemented carbide prepared in comparative example 1.

Detailed Description

Example 1:

wet grinding silicon carbide powder which accounts for 0.6 wt% of the total weight and has the particle size of 0.6 mu m for 6 hours in advance, then adding 10 wt% of cobalt powder, 10 wt% of nickel powder and the balance of tungsten carbide powder, wet grinding for 18 hours, and spray drying and pressing the wet-ground mixture for molding; and sintering the pressed compact by using a low-pressure liquid phase with 1450 ℃, the pressure intensity of 0.6MPa and the heat preservation time of 1h to obtain the Si-reinforced Co-Ni bonding phase reinforced hard alloy.

The microstructure of the cemented carbide prepared in this example was characterized and shown in fig. 1, in which the ordered phase was a strengthening phase and the phase structure was A3B (where a represents Co and/or Ni elements and B represents Si element).

Comparative example 1

The preparation process was substantially the same as in example 1, the formulation of which is shown in Table 1. The bending strength of the comparative example 1 (the existing Co-Ni binding phase hard alloy) and the hard alloy prepared in the example 1 at room temperature is shown in FIG. 2, and as can be seen from FIG. 2, the bending strength of the hard alloy prepared in the example 1 is obviously better than that of the comparative example 1; the bending strength of the hard alloy prepared in the example 1 at high temperature is obviously lower than that of the hard alloy prepared in the comparative example 1, and the bending strength of the hard alloy prepared in the example 1 is kept above 2400 MPa at high temperature of 900 ℃, so that the hard alloy has very good mechanical properties, as shown in FIG. 3. The microstructure of comparative example 1 is shown in FIG. 4, and no strengthening phase is precipitated in the binder phase.

Comparative example 2:

comparative example 2 is prepared by substantially the same procedure as in example 1 except that the silicon carbide powder is added in an amount of 0.5 wt%.

As can be seen from a comparison between example 1 and comparative example 1, when the addition amount of the silicon carbide powder is decreased from 0.6 wt% to 0.5 wt%, since the silicon carbide addition amount is too small, the precipitation strengthening phase content is drastically decreased, thereby decreasing the binder phase strengthening effect. The bending strength is reduced from 3200MPa to 2750MPa, and the bending strength is reduced by 450 MPa.

Comparative example 3:

comparative example 3 the procedure of the preparation method of the alloy of example 3 was substantially the same, except that the silicon carbide powder was added in an amount of 2.6 wt%.

As can be seen from a comparison between example 3 and comparative example 3, when the addition amount of the silicon carbide powder is increased from 2.5 wt% to 2.6 wt%, a brittle phase is easily generated due to an excessive addition amount of silicon carbide, and the flexural strength property of the alloy is rather lowered. The bending strength is reduced from 3300MPa to 2700MPa and 500 MPa.

Examples 2 to 9

The preparation processes of examples 2 to 9 are substantially the same as those of the examples, and the specific ratios and process parameters thereof are shown in table 1.

Table 1 examples 1-9 and some comparative examples the production parameters for the cemented carbide regeneration process

Claims

1. The hard alloy is characterized by consisting of, by mass, 13-15 wt% of cobalt, 13-15 wt% of nickel, 0.6-2.5 wt% of silicon carbide and the balance of tungsten carbide.

2. The cemented carbide with a Si-strengthened Co-Ni based binder phase according to claim 1, characterized in that the grain size of the silicon carbide is 0.6-3.0 um.

3. The cemented carbide with Si reinforced Co-Ni based binder phase according to claim 1, characterized in that it consists of, in mass percent, 13 wt% cobalt, 13 wt% nickel, 0.6 wt% silicon carbide and the balance tungsten carbide.

4. The cemented carbide with Si reinforced Co-Ni based binder phase according to claim 1, characterized in that it consists of, in mass percent, 15 wt% cobalt, 15 wt% nickel, 1.5 wt% silicon carbide and the balance tungsten carbide.

5. The method of producing a cemented carbide with a Co-Ni based binder phase strengthened by Si according to any one of claims 1 to 4, comprising the steps of:

firstly, carrying out pre-wet grinding on silicon carbide powder, then adding cobalt powder, nickel powder and tungsten carbide powder according to a ratio, and continuously carrying out wet grinding; after wet milling is finished, spray drying and compression molding are carried out to obtain a pressed blank; and (3) carrying out low-pressure liquid phase sintering on the pressed compact at a set temperature, and obtaining the hard alloy of the Si-reinforced Co-Ni-based binding phase after sintering.

6. The method for preparing a hard alloy through Si-reinforced Co-Ni based binder phase according to claim 5, wherein the pre-wet milling time is 6-12 h, the continuous wet milling time is 18-36 h, the sintering temperature is 1350-1450 ℃, the pressure at the sintering temperature is 0.6-1.0 MPa, and the sintering holding time is 1-2 h.

7. Use of a hard alloy of Si-reinforced Co-Ni based binder phase according to any of claims 1 to 4 as a material for the manufacture of high temperature resistant molds, rolls and tools.