JPS636617B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a method for producing a titanium carbonitride-based cermet sintered material that has excellent toughness and wear resistance and contains extremely small amounts of bonding metal. Conventionally, hard sintered materials have been proposed in which carbides of group 4a, 5a, and 6a transition metals of the periodic table are used as a hard dispersed phase, and these are bonded with iron group metals as binder phase forming components. Cemented carbide such as WC-Co based, WC-TiC-TaC-Co based, TiC-Mo mainly based on titanium carbide
−Ni-based, further containing titanium nitride
Hard sintered materials such as cermets such as TiC-TiN-Mo-Ni have relatively excellent wear resistance and toughness, so they can be used as cutting tools and wear-resistant tools.
Furthermore, it is widely used as impact-resistant tools. However, in the field of cutting tools, for example, there has been a trend in recent years to require cutting at high cutting speeds to improve productivity, but hard sintered materials such as cemented carbide and cermets have excellent toughness. However, due to insufficient wear resistance, it does not have a satisfactory service life when used under harsh conditions such as high-speed cutting. Therefore, attempts have been made to use ceramic sintered materials mainly made of aluminum oxide, which have sufficient wear resistance, in the above-mentioned fields, but since these ceramic sintered materials have poor toughness,
The current situation is that its uses are limited. On the other hand, attempts have been made to improve the wear resistance of the above-mentioned cemented carbide, which has excellent toughness, by reducing the amount of bonded metal, and it is true that the wear resistance is improved by reducing the amount of bonded metal. However, on the other hand, the sinterability decreases,
To produce dense sintered materials, it is necessary to use a hot pressing method. However, when using the hot press method, the sintered material must be cut in order to manufacture final products that require various shapes, and the above materials are difficult to grind, making it difficult to manufacture industrially. Mass production is extremely difficult. Therefore, from the above-mentioned point of view, the present inventors have developed a method to ensure high wear resistance without using the hot press method and with an extremely small amount of bonding metal, in order to enable efficient industrial production. However, as a result of conducting research to obtain a hard sintered material with a finer hard dispersed phase and excellent toughness, we found that titanium carbonitride powder contains 1 to 40% by weight of molybdenum carbide powder.
A mixed powder obtained by blending 0.1 to 5% by weight of one or more of iron powder, nickel powder, and cobalt powder is molded, and the molded body is heated for 1500 to 500 ml in an atmosphere containing nitrogen. We have discovered that when sintered at a relatively high temperature of 1900°C, a cermet sintered material with excellent toughness and wear resistance, with pores of A-3 or less (ASTM standard), can be obtained with an extremely small amount of binding metal. Ta. This invention was made based on the above knowledge, and includes molybdenum carbide powder: 1 to 40% by weight,
Contains 0.1 to 5% by weight of one or more of iron powder, nickel powder, and cobalt powder,
A mixed powder having a composition in which the remainder is titanium carbonitride is molded into a powder compact of a predetermined shape, and then heated in a nitrogen-containing atmosphere (preferably _N2 of 10 torr or more).
sintered at a temperature of 1500-1900℃ under partial pressure),
The present invention is characterized by a method for producing a titanium carbonitride-based cermet sintered material with pores of A-3 or less (ASTM standard) and excellent toughness and wear resistance. Next, the reason why the mixing ratio of the mixed powder and the sintering temperature are limited as described above in the method of the present invention will be explained. (a) Molybdenum carbide powder Molybdenum carbide (hereinafter referred to as Mo ₂ C) is
Titanium carbonitride (hereinafter referred to as TiCN) particles, which are the main component of the cermet of the present invention, are surrounded by (Ti,
Forming a surrounding tissue consisting of Mo)・(C,N),
It has the effect of increasing the bonding strength of crystal particles and, as a result, increasing the toughness of the cermet, but if the content is less than 1% by weight, the desired effect cannot be obtained;
If it exceeds 1% by weight, the abrasion resistance of the cermet becomes poor, so the blending ratio was set at 1 to 40% by weight. (b) Iron group metal powder Iron, nickel and cobalt have the effect of improving the sinterability of the cermet of the present invention and, as a result, increasing the toughness of the cermet, but if their content is less than 0.1% by weight, the desired If the amount exceeds 5% by weight, the abrasion resistance of the cermet becomes poor, so the blending ratio of these powders was determined to be 0.1 to 5% by weight. (c) Sintering temperature If the sintering temperature is less than 1500℃, the cermet will not be densified due to the presence of cavities and pores, resulting in a decrease in the toughness of the cermet.On the other hand, if the sintering temperature exceeds 1900℃, grain growth will occur. The sintering temperature was set at 1,500 to 1,900°C since toughness decreased. As is clear from the above, this invention provides excellent toughness and wear resistance by specifying the raw material components and their blending ratios as described above, and by limiting the sintering temperature as described above. This has the effect that it is possible to manufacture a cermet having the following properties. The invention can be carried out according to conventional powder metallurgy methods, as explained in detail in the following examples. Example 1 As raw material powders, five types of TiCN powder each having an average particle size of 1.2 μm, a Mo ₂ C powder with an average particle size of 1.0 μm, and an iron group metal powder with an average particle size of 2.2 μm were prepared, and these were shown in Table 1. Table ¹ shows the composition shown in Table 1. Cermet sintered materials 1 to 18 of the present invention were manufactured by sintering under the following conditions. For comparison, comparative cermet sintered materials 1 to 3 each have a composition in which the content of one of the constituent components (those marked with * in Table 1) is outside the scope of the present invention. Comparative cermet sintered materials 4 to 7 were also produced under conditions outside the scope of the present invention (marked with * in Table 1). Next, the resulting cermet sintered materials 1 to 18 of the present invention and comparative cermet sintered material 1 were prepared.

【table】

[Table] Regarding samples 7 to 7, the Vickers hardness was measured for the purpose of evaluating wear resistance, the transverse rupture strength was measured for the purpose of evaluating toughness, and the state of pore generation was observed in accordance with ASTM standards. These results are also shown in Table 1. From the results shown in Table 1, the cermet sintered materials 1 to 18 of the present invention are all sufficiently densified and exhibit high values of hardness (wear resistance) and transverse rupture strength (toughness). On the other hand, Comparative Cermet Sintered Materials 1 to 7 were not sufficiently densified and had low hardness and transverse rupture strength, or even though they were densified, they had low transverse rupture strength. I understand. Example 2 From each of the cermet sintered materials 3, 4, 5, 6, 14, 15, and 16 of the present invention produced in Example 1 and comparative cermet sintered materials 1 to 7,
A cutting chip with the shape of SNP432 was prepared and a cutting test was conducted under the conditions shown below, and the flank wear width and rake face wear depth of the cutting edge were measured. Cutting conditions Work material: SNCM8 (H _B 220)

[Table] Cutting speed: 200 m/min Feed: 0.36 mm/rev. Depth of cut: 1.5 mm Cutting time: 10 minutes For comparison purposes, commercially available P10 WC-based cemented carbide, TiC-based cermet sintered material, and Al Cutting chips made of sintered ₂ O ₃ ceramic materials (represented by conventional cutting chips 1, 2, and 3) were tested under the same conditions to measure the above characteristic values. These results are shown in Table 2. From the results shown in Table 2, cutting chips made of cermet sintered material manufactured by the method of the present invention (cutting chips of the present invention) are superior to cutting chips made of cermet sintered material manufactured by the comparative method (comparison). It can be seen that this material has superior wear resistance and toughness compared to conventional cutting chips. As described above, according to the method of the present invention, a cermet sintered material containing a very small amount of bonding metal and having excellent wear resistance (hardness) and toughness (transverse rupture strength) can be It can be manufactured at low cost with high productivity using powder metallurgy, and the cermet sintered material manufactured by this invention can be used particularly as cutting tools and wear-resistant tools that require the above characteristics. In this case, industrially useful effects such as significantly superior performance are brought about.

Claims (1)

[Claims] 1 Molybdenum carbide powder: 1 to 40% by weight, and one or more of iron powder, nickel powder, and cobalt powder: 0.1 to 5% by weight,
After forming a mixed powder having a composition in which the remainder is titanium carbonitride powder into a powder compact of a predetermined shape,
A method for producing a titanium carbonitride-based cermet sintered material having excellent toughness and wear resistance, which comprises sintering at a temperature of 1500 to 1900°C in an atmosphere containing nitrogen.