JPH0248510B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing ceramic materials with excellent heat resistance and wear resistance, and is particularly applicable to cutting tools such as ductile cast iron, and as electrically conductive ceramics, for example. The present invention relates to a method for producing ceramic materials which are also useful as materials for ceramic heaters and electrode materials that require wear and corrosion resistance. [Prior Art] TiC has been known as a high-temperature material that has excellent spalling resistance because it has a high melting point and hardness, and also has low thermal expansion and does not reduce thermal conductivity at high temperatures. However, since TiC is a difficult-to-sinter material, Co,
By adding metals such as Ni, a dense sintered body was obtained only as a cermet. [Problems to be Solved by the Invention] However, since the above-mentioned cermet is a composite, it is dominated by the behavior of the metal phase, and the properties of TiC itself, particularly the high-temperature properties, are not fully utilized. For example, when cutting ductile cast iron, the cermet tip using the aforementioned cermet is used for finishing cutting, but even for finishing cutting, the cutting speed is low.
High-speed cutting exceeding 300 m/min causes rapid wear, large crater wear, and also tends to cause chipping. On the other hand, if the cutting speed is below 150 to 200 m/min, the cutting speed will be lower than that of carbide chips.
Welding occurs and the finished surface becomes rough. [Means for Solving the Problems] The present invention was made to solve the above problems, and aims to provide a method for producing a dense ceramic material that takes advantage of the characteristics of TiC. The first invention comprises 1 to 40% by weight of Al ₂ O ₃ , 0.05 to 8% by weight of a sintering aid, 3 to 35% by weight of ZrO ₂ and/or HfO ₂ , and the following proportions of (a) and ( A mixture consisting of 17 to 95.95% by weight of the TiC component consisting of component (b) and the following component (a) is sintered in a non-oxidizing atmosphere until the metal of component (a) no longer exists as a metal phase to achieve heat and wear resistance. Its purpose is to manufacture ceramic materials. (a) 4 to 30% by weight of a metal consisting of one or more selected from groups 4a, 5a and 6a of the periodic table of elements (b) 70 to 96% by weight of TiC The second invention is the first invention in addition to
The gist is that 5 to 40% by weight of the TiC component is made up of component (c) consisting of Zr, Hf, and one or more carbides selected from groups 5a and 6a of the periodic table of elements. Component (a) of the first and second inventions, that is, metals of groups 4a, 5a, and 6a in the periodic table of elements, are Ti, Zr,
These are Hf, V, Nb, Ta, Cr, Mo, and W. Component (c) of the second invention, that is, Zr, Hf, and carbides of groups 5a and 6a in the periodic table of elements are Zr, Hf, V,
It is a carbide of Nb, Ta, Cr, Mo, and W.
For example, ZrC, HfC, VC, NbC, TaC, CrC ₂ ,
Examples include Mo ₂ C, WC, etc. In the present invention, the absence of metal as a metal phase means that no metal phase is detected at least by an X-ray diffraction device, preferably by an optical microscope. A non-oxidizing atmosphere is the one in the compound during sintering.
There is no particular restriction as long as the atmosphere does not oxidize TiC and the metal of component (a), and examples thereof include N ₂ , Ar, H ₂ and the like. Furthermore, the above-mentioned compound can be sintered not only under normal pressure but also by pressure sintering method or hot isostatic pressing method, and the sintering temperature may be within the range normally used. It is necessary to sinter until the metal phase in the material is no longer present. [Operation] The operation of the first invention will be explained. Al ₂ O ₃ is a chemically stable substance with excellent oxidation resistance and low free energy of formation, and by dispersing it in the TiC component, the oxidation resistance and chemical stability of the ceramic material as a whole can be improved. Can be done. This adds further oxidation resistance and chemical stability to the excellent properties of TiC. In the present invention, Al ₂ O ₃ is used in an amount of 1 to 40% by weight, but if the amount of Al ₂ O ₃ is less than 1% by weight, the above effects will not be sufficiently exhibited, and if the amount is more than 40% by weight,
The characteristics of TiC itself will fade. The reason why the sintering aid is used together with Al ₂ O ₃ in the present invention is that in addition to the above-mentioned effective effects of Al ₂ O ₃ , the Al ₂ O ₃ compound formed by Al ₂ O ₃ and the sintering aid improves the quality of the ceramic material. This is because it assists sintering and improves sinterability. In the present invention, sintering aids include MgO, CaO, SiO ₂ ,
NiO, rare earth oxides such as Y ₂ O ₃ , Dy ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ etc., usually Al ₂ O ₃ series, Al ₂ O ₃ -TiC series,
Refers to those used for sintering Al ₂ O ₃ -based ceramics such as Al ₂ O ₃ -ZrO ₂ series. In the present invention, the sintering aid is 0.05% by weight to 8% by weight.
However, if it is less than 0.05% by weight, the above effect will not be sufficiently exhibited, and if it is more than 8% by weight, a large amount of the Al ₂ O ₃ compound will deteriorate the high-temperature properties of the ceramic material. ZrO ₂ and/or HfO ₂ are usually dispersed in the ceramic material in tetragonal form. When a large external force is applied to a ceramic material, it undergoes a phase transition from tetragonal to monoclinic, and this phase change strengthens the ceramic material by absorbing the external force.
This effect is identical to what is known as diffusionless lattice transformation. In the present invention, ZrO ₂ and/or HfO ₂
It is used in an amount of up to 35% by weight, but if it is less than 3% by weight, the above effects will not be sufficiently exhibited, and if it exceeds 35% by weight, the wear resistance of the sintered body will decrease. Next, the metal component (a) mentioned above is contained in TiC, and this component (a) is dissolved in TiC during the sintering process.
It is necessary that it not be present in the ceramic material as a metallic phase. For this reason, TiC has a non-stoichiometric composition, making the crystal structure incomplete and unstable. It is believed that this facilitates sintering reactions such as solid phase reactions, and as a result, the sinterability of the ceramic material of the present invention was improved. This phenomenon also means that the interface between the Al ₂ O ₃ grains and the TiC grains or between the TiC grains is strengthened. Furthermore, although it is not fully understood yet, it is thought that the high-temperature strength of TiC itself is improved in terms of strength and toughness by changing the bond form from the original covalent bond to a metallic bond. In the present invention, component (a) is used in an amount of 4 to 30% by weight of the TiC component in order to impart the above properties, but if the amount of component (a) is less than 4% by weight of the TiC component, the above effects are insufficient. , and the amount of component (a) is 30% of the TiC component.
If the amount exceeds % by weight, component (a) may remain as a metal phase, and wear resistance decreases in terms of cutting performance. The operation of the second invention will be explained. The second invention includes, in addition to the structure of the first invention, a carbide of the above-mentioned component (c) in the TiC component. This (c) component is
Although it forms a solid solution in TiC, the crystal lattice of TiC is distorted because the atoms contained in TiC and component (c) have different sizes. A crystal lattice plane with such lattice distortion requires more energy for dislocations to move than a flat lattice plane where atoms of the same size are lined up. That is, more energy is required to break the ceramic material, and the strength of the ceramic material is further improved by the above action. To provide the above characteristics in the second invention (c)
The ingredients used are 5 to 40% by weight of TiC, but 5% by weight
If it is less than that, the above characteristics will not be exhibited and the result will be the same as the first invention. On the other hand, if it exceeds 40% by weight,
The excellent properties of TiC itself will deteriorate. [Effects of the Invention] By using the method for producing a ceramic material of the present invention, it is possible to produce a ceramic material that makes full use of the characteristics of TiC and has precise wear resistance and heat resistance. Ceramic materials manufactured by the method for manufacturing ceramic materials of the first invention can be used for cutting tools such as cast iron such as the aforementioned ductile cast iron, steel, high nickel, aluminum, titanium, etc., nonmetallic cutting tools, wear resistance, corrosion resistance, and heat resistance. Useful for mechanical parts that require high performance.
Furthermore, since it is electrically conductive, it is useful as an electrically conductive ceramic, such as in ceramic heaters, and as an electrode material that requires wear resistance and corrosion resistance. In addition to the effects of the ceramic material manufactured according to the first invention, the ceramic material manufactured by the method for manufacturing ceramic material of the second invention has Zr, Hf,
By adding Group 5a and 6a carbides, excellent properties such as toughness, hardness, heat resistance, and wear resistance can be added. However, all these properties are the first
The addition of ZrC, HfC or VC improves hardness and wear resistance, the addition of TaC or NbC improves heat resistance, and the addition of WC, Mo ₂ C, CrC ₂ improves toughness. are improved over the ceramic material of the first invention. Therefore, Zr, Hf, 5a, 6a depending on the use etc.
By selectively adding group carbides, it is possible to add superior properties to the excellent properties of the ceramic material according to the first invention, and it is possible to obtain ceramic materials that are more useful as various materials. [Example] An example of the present invention will be described. Samples in Table 1 as Examples of the First Invention
The mixture was prepared in the proportions shown in Nos. 1-a to 1-k, and in the proportions shown in Samples Nos. 2-a to 2-k as an example of the second invention, and mixed with acetone in a stainless steel ball mill.
Wet milling was carried out for 30 hours. Thereafter, acetone was volatilized in a dryer, and the material was pulverized in a mortar until the entire amount passed through 60 meshes to prepare a base powder. The amount of component (a), (b) or (c) in the TiC component in Table 1 is the TiC component.
It is weight % when it is set as 100. In addition, α−Al ₂ O ₃
As a sintering aid, use one with a purity of 99.5% or more; for ZrO ₂ use one with an average particle size of 0.6 μm; for HfO ₂ use one with an average particle size of 1.5 μm. , the component (a) mentioned above passes through 325 meshes,
The TiC component (b) had an average particle size of 1.1 μm and a total carbon content of 19.4%, and the component (c) used in the embodiment of the second invention had passed 325 meshes. This base powder was sintered according to the sintering temperature and sintering method shown in Table 1. The sintering method used in this example was as follows: 1. Sintered in a graphite mold using a pressure sintering method at a pressure of 200 Kg/ml and a pressure firing time of 15 minutes. (Indicated as H・P in the table.) 2 Sintering for 1 hour in a reduced pressure argon atmosphere. (In the table, it is described as normal sintering.) 3. Primary sintering was performed for 1 hour in a reduced pressure argon atmosphere, and then sintered by hot isostatic pressing under conditions of 1500°C and 1500 atmospheric pressure holding time. (In the table, HIP
It was written. ) It was. The sintered body thus obtained was polished to SNGN432TN with a diamond grindstone to a surface of 3S or less (according to JIS), the theoretical density and hardness were measured, and a cutting test was conducted according to the cutting test conditions shown in Table 2. Ivy.
The work material is 400mm long, as shown in Figure 1.
It has a rod shape with a diameter of 150 mm, and six grooves each having a width of 5 mm are provided at equal intervals in the longitudinal direction. Furthermore, the state of component (a) in the sintered body thus obtained was examined using an X-ray diffraction device and an optical microscope. Furthermore, the formulation was used as a comparative example of the first invention.
In the proportions shown in Sample Nos. 1'-a to 1'-i in the table, and as comparative examples of the second invention, Samples No. 2'-a to 1 in Table 1.
Each material was blended in the proportion shown in 2'-f, sintered and molded in the same manner as in the example, and the theoretical density and hardness were measured and a cutting test was conducted. In addition, the state of component (a) was examined using an X-ray diffraction device or the like in the same manner as in the Examples. However, a commercially available TiC cermet was used.

【table】

【table】

[Table] Sample No. 1-a to 1-k and sample No. 1'-a in Table 1
By comparing with ~1'-i and comparing Samples No. 2-a to 2-k and Samples No. 2'-a to 2'-f, we made use of the properties of TiC and produced a dense ceramic material. contains Al ₂ O ₃ , sintering aid, ZrO ₂ and/or
It is necessary to keep the amounts of HfO ₂ and the components (a) and (b) in the TiC component, and in the case of the second invention, the components (a), (b), and (c), to predetermined amounts, and the above ( It has been found that it is necessary to sinter so that component a) no longer exists as a metallic phase. In addition, when measuring the electrical conductivity of the ceramic material manufactured by the method of manufacturing the ceramic material of the present invention,
Although it varied depending on the composition, it was approximately 50 to 100×10 ⁻⁶ Ω·cm. This can be said to have one of the best electrical conductivity among conventional ceramic materials for practical use. Furthermore, when the effect of the second invention was measured,
In the first invention, as in sample No. 1-h and sample No. 2-j,
It was confirmed that the ceramic material produced by adding WC, MO ₂ C or CrC ₂ as the component (c) has superior toughness compared to the ceramic material according to the first invention, so that the number of impacts in the cutting test increases. Also, the first
It has been confirmed that when ZrC, HfC or VC is added as component (c) to the invention, the hardness becomes higher than that of the ceramic material according to the first invention. Furthermore, the first
It has been confirmed that when TaC and NbC are added as component (c) to the invention, there is less decrease in heat resistance, that is, strength at high temperatures, compared to the ceramic material according to the first invention. Incidentally, when sintered bodies were similarly prepared and tested for compounds having the compositions of the present invention that are not listed in Table 1, the number of impacts until breakage was similarly significantly increased compared to the conventional one. It was confirmed that

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a workpiece used in an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1 1 to 40% by weight of Al ₂ O ₃ , 0.05 to 8% by weight of a sintering aid, 3 to 35% by weight of ZrO ₂ and/or HfO ₂ , and (a) in the following proportions: (b) TiC component 17 consisting of component
95.95% by weight, and sintering in a non-oxidizing atmosphere until the metal of component (a) no longer exists as a metal phase. . (a) 4 to 30% by weight of a metal consisting of one or more selected from groups 4a, 5a and 6a of the periodic table of elements (b) 70 to 96% by weight of TiC 2 The sintering aid is MgO, The method for producing a heat-resistant and wear-resistant ceramic material according to claim 1, which is one or more selected from CaO, SiO ₂ , NiO, and rare earth oxides. 3 1 to 40% by weight of Al ₂ O ₃ , 0.05 to 8% by weight of sintering aid, 3 to 35% by weight of ZrO ₂ and/or HfO ₂ , and the following proportions of (a), (b) and (c) ) component consisting of TiC component
A heat-resistant and wear-resistant ceramic material characterized by sintering a mixture consisting of 17 to 95.95% by weight in a non-oxidizing atmosphere until the metal of component (a) below no longer exists as a metal phase. Manufacturing method. (a) 4-30% by weight of one or more metals selected from groups 4a, 5a and 6a of the periodic table of elements (b) 30-91% by weight of TiC (c) Zr, Hf and elements 5 to 40% by weight of one or more carbides selected from Groups 5a and 6a of the periodic table. 4. The method for producing a heat-resistant and wear-resistant ceramic material according to claim 3, wherein the sintering aid is one or more selected from MgO, CaO, SiO ₂ , NiO, and rare earth oxides. .