JPH0255390B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a material for a thin film magnetic head slider suitable for high-density recording. [Prior Art] Conventionally, disk head sliders for computers have been manufactured by processing ferrite block materials. However, since ferrite material has low high-frequency magnetic permeability, the recording or reproducing output of the magnetic head becomes low when high-speed data transfer or magnetic circuits are formed using thin films. However, in recent years, there has been a trend to reduce the inductance of the disk head so that it can operate in a higher frequency range, and to reduce the gear width to improve high-speed transfer and recording density. Currently, in response to higher recording densities, thin film magnetic heads are being developed. A summary of the characteristics required for thin-film magnetic head substrates include the following items. (1) The crystal grains are fine, uniform, and dense, and there are no pores. (2) Excellent compatibility with recording media, lubricity, and wear resistance. (3) Good machinability. In other words, it must be free-cutting and have excellent precision machinability. (4) Good compatibility with the material coated on the surface. Following this trend, products containing aluminum oxide and titanium carbide as main components (JP
66403) and composite materials in which titanium nitride is partially dissolved in titanium carbide have been developed. In addition to the above ingredients, in order to improve the sinterability of the material, MgO, CaO, which is effective as a grain growth inhibitor or sintering accelerator for aluminum oxide,
NiO etc. are added. For such materials for thin film magnetic heads,
Since the substrate is used after being finished with an ultra-precision mirror finish, it is particularly required that there are no even minute pores on the substrate surface when the substrate is finished with an ultra-precision mirror finish, and that the substrate is easy to be precisely machined. ing. Therefore, in order to prevent the presence of minute pores in a substrate with an ultra-precision mirror finish, the ceramic mixed powder is sintered to almost the theoretical density, and the bonding within the ceramic crystal particles is strong and the fine structure is created. It is necessary to create On the other hand, a ceramic sintered body having such density and structure has very poor machinability. In order to solve this problem, a material has been developed in which a free-machining agent is added to a system mainly composed of aluminum oxide and titanium carbide (Japanese Patent Laid-Open No. 1983-1999).
No. 135772). [Problems to be solved by the invention] However, since this composite ceramic is composed of aluminum oxide and titanium carbide, it has the disadvantage of being hard and brittle, and is prone to chipping during precision machining. In comparison, there was a problem of inferior mechanical workability (free machinability). The present invention was made in order to cope with the above-mentioned situation, and it is possible to process an aluminum oxide-titanium carbide composite material into a thin-film magnetic head slider more precisely and quickly without causing chipping due to processing. The purpose of this invention is to improve the properties of aluminum oxide-titanium carbide composites. [Means for solving the problem] In order to meet the object, the present invention improves chipping resistance during precision machining by specifying the content of titanium carbide in the aluminum oxide-titanium carbide system to be 45 to 75% by weight. The aim is to improve sexual performance. Furthermore, in addition to the basic composition of this aluminum oxide-titanium carbide system, 0.5 to 5% by weight of one or more of oxides of Mg, Ca, B, Ni, Cr, and Zr as a free machining agent, and sinterability. to improve
If necessary, 0.05 to 2 parts by weight of aluminum-yttrium composite oxide in terms of Y ₂ O ₃ is added. In addition, the amount of oxygen solid solution in titanium carbide of aluminum oxide-titanium carbide system is TiO ₂
Alternatively, if the content is suppressed to 15% by weight or less in terms of titanium carbonate, the fracture toughness of ceramics will be improved.
Furthermore, 2 to 20% by weight of the titanium carbide is replaced with one or more of carbides (excluding titanium carbide), nitrides, borides, and composite compounds of metals in groups A, A, and A of the periodic table. As a result, fine crystal particles are generated. The ceramic material thus obtained has a 5.5 MPam
It has a fracture toughness value of That is, in the composite ceramic of the present invention, the bonding force between aluminum oxide and titanium carbide is strengthened to prevent chipping when processing the ceramic material into a magnetic head slider. This aluminum oxide-titanium carbide is used as a basic composition, and various properties of the ceramic material having the basic composition are appropriately improved with optional additive components. Here, the components of the present invention and their composition ranges will be explained in detail. In this invention, titanium carbide is the main component of this material along with aluminum oxide, and 45% by weight
If it is less than that, chipping tends to occur during precision machining, and the fracture toughness value also decreases. On the other hand, if it exceeds 75% by weight, the sintering temperature will be high, the crystal grain size of aluminum oxide will be large, the fracture toughness will be low, chipping will easily occur during machining, and titanium carbide will not be suitable as a material for magnetic heads. The oxygen solid capacity contained in the final sintered body of the titanium compound is undesirable because if it exceeds 15% by weight in terms of titanium oxide, it tends to reduce fracture toughness and cause chipping during precision machining. . However, oxygen present in the titanium compound is important for increasing the bonding strength between the aluminum oxide and titanium carbide components and obtaining a tough sintered body. Aluminum oxide is the main component of this material along with titanium carbide, and due to the limited content range of titanium carbide,
% by weight. In the machining method, it is preferable to add one or more of various oxides such as Mg, Ca, B, Ni, Cr, and Zr as a free-cutting agent, so that the effect can be observed and the optimum amount thereof can be observed. is 0.5 to 5 parts by weight. That is, if it is less than 0.5 part by weight, the effect of suppressing the grain growth of aluminum oxide is observed and a dense sintered body can be obtained, but no improvement in machinability is observed. Moreover, if it exceeds 5 parts by weight, the bonding strength between the crystal grains of the sintered body becomes weak, which is not preferable. As for zirconium oxide, unstabilized ZrO ₂ with a particle size of 0.3 μm or less, ZrO ₂ partially stabilized with at least one of Y ₂ O ₃ , MgO, CaO, and CeO, or stabilized ZrO ₂ may be used. These ZrO ₂ have effects on ultra-precision machinability by suppressing grain growth and improving toughness, and also improve compatibility with recording media.
Although it has excellent lubricity and wear resistance, addition of 5 parts by weight or more has a significant negative effect on workability. Aluminum-yttrium composite oxide is
If it is less than 0.05 part by weight (calculated as Y ₂ O ₃₎ , it will not have the effect of promoting mutual sinterability between aluminum oxide and other main ingredients, and if it exceeds 2 parts by weight, pores will be created in the sintered body, and the sintered body will be damaged. The fracture toughness of the steel decreases, making chipping more likely to occur during machining. Therefore, the effect as a sintering accelerator is seen in the range of 0.05 parts by weight to 2 parts by weight. Further, as the aluminum-yttrium composite oxide powder, for example, as one of the composite oxides, it can also be used in the form of garnet shown in the following formula. Y ₃ (AlY) ₂ (AlO ₄ ) ₃ ...(1) (YAl) ₃ Al ₂ (AlO ₄ ) ₃ ...(2) Similarly, garnet with the composition Y ₃ Al ₂ (AlO ₄ ) ₃
A composition represented by Y _x Al _(1-x) O ₃ (where x<1) can also be used. A part of titanium carbide can be made into carbides (excluding titanium carbide), nitrides, etc. of metals in groups a, a, and a of the periodic table.
Substitution with borides and their respective composites is also possible. In that case, in order to retain the characteristics of the aluminum oxide-titanium carbide composite material and further refine the crystal grains, 2 to 20% by weight of titanium carbide should be used.
The effect can only be seen after replacing. In other words, substitution of less than 2 parts by weight has no effect, and 20 parts by weight.
If the amount exceeds 1 part by weight, sinterability deteriorates, and the fracture toughness of the sintered body obtained by force is low, resulting in poor precision workability. Therefore, when replacing a part of titanium carbide with carbides (excluding titanium carbide), nitrides, borides, and their respective composite compounds of metals in group a, a, a of the periodic table, In the range of ~20% by weight, the characteristics of the Al ₂ O ₃ --TiC system can be retained and the characteristics of the third component can be utilized. In addition, if the amount of metal or oxide-based impurities mixed in during the manufacturing process exceeds 0.5 parts by weight,
This inevitably increases the amount of magnetic impurities, which is undesirable when used as a slider material for a thin film magnetic head. Further, these materials are manufactured through a sintering process after adjusting the raw material mixture powder. Sintering is preferably performed by a hot press sintering method such as a hot press method or a hot isostatic sintering method. In the case of the hot press method, the pressure is 50 to 350 Kg・f/cm ² and the firing temperature is 1550 to 1800°C, while in the hot isostatic sintering method, the pressure is 500 Kg・f/cm ² or more and the temperature is 1450 to 1600°C. Good results can be obtained below. The sintered body thus obtained has a theoretical density of 99
% or more, it is extremely dense, has almost no pores, has a fine grain size, and has excellent mechanical workability with fracture toughness of 5.5 AMam ^1/2 or more. It also does not cause pitting during processing and has excellent workability during precision processing. In addition, the material sintered by the hot pressing method or hot isostatic sintering method is heated in a non-oxidizing atmosphere at a pressure of 0 to 10 kg/cm ² and at a temperature of 1000°C to 100° below the sintering temperature.
Strain can be removed by heat treatment in a temperature range as high as 0.degree. Therefore, the heat-treated material does not cause fine chipping due to strain during precision processing, and the coating film has good adhesion, making it possible to obtain an extremely excellent material. [Example] The manufacturing method of the magnetic head substrate material of the present invention and its precision machining performance will be explained with reference to Examples. -Experiment 1- Raw material powder adjusted to the following component compositions (1) to (21) [α-Al ₂ O ₃ : average particle size 0.3 μm, purity 99.9
%, titanium compound (TiC, TiO ₂ ): average particle 0.5μ
m, TiC・TiO ₂ solid solution, MgO, ZrO ₂ , Al ₂ O ₃・
Y ₂ O ₃ solid solution sintering accelerator and free machinability imparting agent, carbides and nitrides of metals from groups a, Va, and a of the periodic table;
Boride: average particle diameter 0.8 μm,
℃) and a pressure of 200 Kg/cm ² was applied and maintained for 60 minutes.
50 x 50 then by removing the pressure and allowing to cool
A desired sintered body of 5.5 mm was obtained. Each sintered body was cut and ground with a diamond whetstone to prepare test pieces, which were subjected to various tests. Fracture toughness is measured using IF, which is determined from the length of the crack that occurs on the diagonal extension of the Vickers indentation.
The Indentation Fracture Method was used.
The surface of the test piece was ground with a diamond wheel and then mechanically polished to a mirror finish. The test load was 10 kgf in all cases, and the loading time was 20 seconds. Precision machinability means that chips on the edges occur when machining to match the track width of the disk head slider and are undesirable for use, are marked with an ×, and those that have almost no chipping and are not a problem in use are marked as △. , Particularly good results are marked with a circle. Free machinability is indicated by a mark ○ if the time required to cut the same cross-sectional area is short, and a mark x if the cutting time is long and is unfavorable in terms of productivity. For fracture toughness, 5.5 MPam ^1/2 or more is indicated by ○, and less than 5.5 MPam 1/2 is indicated by ×. Regarding relative density, those sintered under the above conditions and which cannot be sintered to the level of wear resistance required for a slider are marked with an "X", those that can be used are marked with a △, and those with particularly excellent properties are marked with an ○. Indicated by
These results are shown in Table 1.

【table】

[Table] -Experiment 2- Table 2 shows the free machinability imparting agents MgO, Cr ₂ O ₃ ,
The results of investigating the effects of NiO, ZrO _2, etc. are shown. Note that the test piece was created in the same manner as in Experiment 1. Further, the workability test was conducted by the method shown in FIG.

【table】

【table】

[Table] -Experiment 3- Table 3 shows the relationship with the pores present in the sintered body when sintered at a constant hot press temperature. -Experiment 4- After the prepared raw material powder used in Experiment 1 was sintered by a hot press method, the pressure was removed and heat treatment was performed at a temperature 50° C. higher than the hot press sintering temperature. Similarly, the prepared raw material powder used in Experiment 1 was sintered to a relative density of 95% using the hot pressing method, and then heated to a temperature lower than the hot pressing temperature using the hot isostatic pressure HIP sintering method.
Sintering was performed at a temperature 100°C lower. Next, heat treatment was performed at 1300°C in a non-oxidizing atmosphere. Next, the precision workability of these materials and the adhesion of the coating film were evaluated. Precision workability was evaluated by cutting the material with a diamond cutting wheel and observing fine chipping at the corners. Those with chipping are marked with an "X", those with no chipping are marked with a "○", and those with particularly excellent results are marked with a "◎". In addition, Al ₂ O ₃ and Senda coating were performed, and those with excellent coating film adhesion are marked with ○, and those with poor adhesion are marked with △.

【table】

【table】

〔Effect of the invention〕

The aluminum oxide-titanium carbide composite material of the present invention has greater fracture toughness than conventional aluminum oxide-titanium carbide composite materials, so it can be processed efficiently without chipping when processed into magnetic head sliders. It has excellent performance in precision processing and machinability as a material for magnetic head sliders.

[Brief explanation of the drawing]

Figure 1 shows a device used to test the difficulty of processing materials for magnetic head boards.A load of 1.2 kg is applied to one end of a GC board with a sample attached, the sample and GC board are cut, and the time required for cutting is measured. This is a device that determines workability. 1: Diamond cutting wheel (#325 metal bond φ150mm), 2: Magnetic head board material (size 50 x 50 x 2.6t mm), 3: GC plate, 4: Load 1.2Kg.

Claims (1)

[Scope of Claims] 1. A basic material containing 45 to 75% by weight of titanium carbide, in which 15% by weight or less of the titanium carbide is replaced with a titanium oxide or carbonate, and the remainder is aluminum oxide. For 100 parts by weight of the composition, magnesium, calcium, boron,
0.5 to 5 parts by weight of one or more selected from the group of oxides of nickel, chromium, and zirconium;
Equivalent amount of yttrium oxide as a sintering accelerator
A magnetic head substrate material containing 0.05 to 2.0 parts by weight of aluminum-yttrium composite oxide. 2. In the statement of claim 1, a part of titanium carbide is specified as a periodic table a, excluding titanium carbide.
A material for a magnetic head substrate, which is substituted with one or more of carbides, nitrides, borates, and composite compounds of group a and a metals. 3. For 100 parts by weight of a basic composition containing 45 to 75% by weight of titanium carbide, the remainder consisting of aluminum oxide, and 2% by weight or less of the aluminum oxide being replaced with an aluminum-titanium composite oxide,
Magnesium, calcium,
Aluminum-yttrium composite oxide containing 0.5 to 5 parts by weight of one or more selected from the group of oxides of boron, nickel, chromium, and zirconium, and 0.05 to 2.0 parts by weight in terms of yttrium oxide as a sintering accelerator. A material for magnetic head substrates made of a combination of substances. 4 In the statement of claim 3, a part of titanium carbide is classified into periodic table a, excluding titanium carbide.
A material for a magnetic head substrate, which is substituted with one or more of carbides, nitrides, borates, and composite compounds of group a and a metals.