JP2000178026A - Powdery multiple titanium compound and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a powdery titanium compound useful as a base material component of a friction material for an automotive brake device, or the like. SOLUTION: This powdery multiple titanium compound consists of combined crystal grains each of which is formed by joining together a crystal grain of an alkaline earth metal titanate represented by the formula RTiO3 (wherein R is Mg, Ca, Sr or Ba) and a crystal grain of a hollandite type octotitanate represented by the formula AXMYTi8-YO16 (wherein: A is an alkali metal element or Ba; M is Al, Fe, Cr, Ga, Mg, Co, Ni, Cu or Zn; X is a numerical value of 0.5-3; and Y=X/2 when M is a divalent element and Y=X when M is a trivalent element). The production process of the powdery multiple titanium compound comprises: mixing powdery TiO2, A2O, RO and MO* (wherein MO* is MO or M2O3) together to obtain a powdery mixture; granulating the powdery mixture into granules; subjecting the granules to firing treatment at 1,300-1,500 deg.C; and thereafter, subjecting the fired material to disintegrating treatment to produce the objective powdery titanium compound. As an effect of the combined crystal structure, for example, frictional wear characteristics (such as friction coefficient, wear resistance and mating surface damage property) of a friction material for a brake device can be enhanced by using this titanium compound as a base material component of the friction material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite titanium compound powder, more specifically, a composite material having a composite particle structure in which crystal grains of alkaline earth metal titanate and crystal grains of octotitanate are combined, and a friction material is constituted. The present invention relates to a composite titanium compound powder useful as a material and the like and a method for producing the same.

[0002]

2. Description of the Related Art Alkaline earth metal titanates: RTiO ₃ [R: alkaline earth metal] as synthetic titanic acid inorganic compounds, octotitanate having a hollandite structure: A _X
M _X Ti _8-X O ₁₆ [A: Alkali metal, M: Mg, Z
n, Fe, Al, etc., x=0.5 to 3] and the like are known.
Since the alkaline earth metal titanate is a compound having a high dielectric constant, it is practically used as a material in the field of electronics such as dielectrics and piezoelectrics. This compound is produced by a method such as firing a mixture of titanium dioxide and an alkaline earth metal oxide (JP-A-56-162403, JP-B5-27571 and the like). Hollandite octotitanate is a compound that has a high melting point and low thermal conductivity, is excellent in strength and chemical stability, and is useful as a heat-resistant material, heat insulating material, reinforcing material, etc. It is produced by a method such as firing a mixture of oxides and alkaline earth metal oxides (Japanese Examined Patent Publication No. 62-41176, Research Report of the Institute for Inorganic Materials No. 57, pages 4-7).

[0003]

The above-mentioned synthetic inorganic titanate compound is a useful industrial material having physical properties based on its chemical composition and crystal structure, but its use is limited.
INDUSTRIAL APPLICABILITY The present invention enables expansion and diversification of engineering applications of titanic acid-based synthetic inorganic compounds. For example, as a constituent material of a friction material, an automobile brake device can be made smaller and lighter, and a braking function can be improved and stabilized. The present invention provides a titanium compound powder having improved material properties and functions, which can obtain good friction and wear characteristics required for the above, and a method for producing the same.

[0004]

[In the formula, A is one or more elements selected from alkali metal elements and Ba, M is one or more elements selected from Al _, Fe, Cr _, Ga _, Mg _, Co _, Ni _, Cu _and Zn. 2 or more elements, X = 0.5 to 3, Y = X/2 (when M is a divalent element), Y = X (when M is a trivalent element)]

It is characterized by comprising composite crystal particles in which the crystal grains of the hollandite-type octotitanate represented by

The complex compound powder of the present invention comprises a powder of alkaline earth metal titanate (RTiO ₃ ) [1] and a powder of octotitanate (A _X M _Y Ti _8-Y O ₁₆ ) [2]. Unlike a mere mixture, it is a powder composed of composite crystal particles in which these two types of crystals are bonded. As an effect of the particle structure, it has material properties and functions different from those of the mere mixed powder, and when applied as a base material component of a friction material of an automobile brake device, for example, a friction coefficient that cannot be obtained with the mere mixed powder, It is possible to obtain improved properties such as wear resistance and opponent attack (reference example below).

The composite compound powder of the present invention is manufactured by a firing process. The starting material is titanium dioxide (TiO 2
₂ ) or a titanium compound that produces TiO ₂ by heating,
Alkali metal oxide (A ₂ O) or an alkali metal compound that produces A ₂ O by heating, BaO or B by heating
a barium compound that generates aO, an alkaline earth metal oxide (RO) or an alkaline earth metal compound that generates RO by heating, and an M element oxide (MO ^* ) or MO ^* (MO ^* is MO or M ₂ ) by heating. It is prepared by compounding O ₃ )-producing compounds in the required ratios.
The raw material powder mixture is granulated and subjected to a firing treatment as granulated powder having an appropriate particle size. Processing temperature is 1300-150
It is 0°C.

In the firing process, TiO ₂ in the starting material
And RO produce an alkaline earth metal titanate compound [1] by the reaction of the following formula [I], and TiO ₂ , A ₂ O and MO ^* are octotitanate [2] by the reaction of the following [II]. To generate. TiO ₂ +RO → RTiO ₃ [I] [wherein R is as defined above] (8-Y) TiO ₂ +(x/2) A ₂ O + Y MO ^* → A _X M _Y Ti _8-Y O ₁₆ ... [II] [In the formula, A, M, x _{, and} Y are as defined above]

The production ratio of the crystal phases of RTiO ₃ [1] and A _X M _Y Ti _{8- Y} O ₁₆ [2] constituting the composite particles in the above firing treatment is controlled by the raw material blending ratio. Also, these crystals that are produced are fine (the crystals of alkaline earth metal titanates are of the order of submicrons, those of octotitanate are of the order of a few microns). The formation of fine crystals is due to mutual inhibition of crystal growth in the course of complex precipitation by the firing reaction. The composite particles obtained through the calcination process have substantially the same particle morphology (shape/size) as that of the granulated powder subjected to the calcination process.

[0009]

DETAILED DESCRIPTION OF THE INVENTION is used for the preparation of departure material the titanium compound, purified anatase, purified rutile, halides, and the like hydrates, alkali metal compound, N
Examples thereof include oxides such as a, K, Li, Rb and Cs, carbonates, halides and hydroxides. R element compounds include C
Oxides such as a, Sr, and Mg, carbonates, halides, and hydroxides are used, and the M element compound is Al, Fe,
Oxides such as Cr and Ga, carbonates, halogen compounds and hydroxides are used. The raw material powder preferably has a fine particle diameter of about 10 μm or less in average diameter in order to efficiently perform the firing reaction. The starting raw material powder adjusted to have a predetermined composition is subjected to firing treatment by dry or wet granulation as granulated powder having an appropriate particle size (for example, average particle size of about 10 to 100 μm).

The firing treatment is carried out at a temperature of about 1300 to 1500° C.
It is carried out by holding for a suitable time (for example, 1 to 4 hours). The firing temperature is set to 1300° C. or higher even if RTiO ₃ crystals can be formed at lower temperatures,
_This delays the formation reaction of _{X MY} Ti _8-Y O ₁₆ or causes a shortage of the reaction production amount, and as a result, it becomes difficult to obtain a composite compound powder having a phase structure corresponding to the component mixing ratio of the starting materials. Is. Further, the upper limit of the processing temperature is 1500
The reason why the temperature is set to ℃ is that if the temperature exceeds this temperature, agglomeration due to sintering of particles progresses, and mechanical processing means is required for crushing the fired product after the processing, and the processing operation becomes complicated.

After the firing treatment, the fired product is subjected to a vibrating sieve or the like.
By carrying out a mild crushing treatment, alkaline earth titanate
Metals (RTiO₃ ) Crystal grains and octotitanate (A
_X M _Y Ti_8-Y O₁₆) From composite particles in which the crystal grains of
To obtain a powder. The shape and particle size of the obtained composite particles are
It is almost the same as that of the granulated powder that was subjected to the grain-forming treatment. Sanawa
The particle morphology of the granulated powder is almost the same as that of the composite particles after firing.
It is inherited as it is. Therefore, depending on the granular form of the granulated powder, the product
The particle morphology of the powder can be controlled.

Composite particles of the composite titanium compound powder of the present invention
Alkaline earth metal titanate (RTiO₃ )When
Octo titanate (A_X M_Y Ti_8-Y O₁₆) Of the crystalline phase
The quantity ratio can be adjusted arbitrarily according to the application of powder, required characteristics, etc.
Be done. Typically RTiO ₃ /A_X M_Y Ti_8-Y O₁₆
(Molar ratio): Given a composition ratio of 1/0.1 to 1/0.2
Be done. The composite titanium compound powder having this composition ratio is
For example, as a base material component of friction materials for automobile braking systems
Titanic acid is preferred and as an effect of its composite crystal structure
Powder of alkaline earth metal or octotitanate alone, or
It is not possible to obtain high
Improved friction coefficient (μ), wear resistance, opponent attack, etc.
Provides friction and wear properties.

[0013]

[Example] Purified anatase powder, alkali metal carbonate,
To prepare a slurry by adding an appropriate amount of water (about twice the weight of the powder) to a powder mixture consisting of alkaline earth metal carbonate and M element oxide, and treat with a wet spray dryer (spray dryer). As a result, a granulated powder (average particle size: about 40 μm) is obtained as a dried product. The granulated powder is put into an alumina crucible and fired in an electric furnace (treatment temperature: 1350° C., treatment time: about 1 hour). After the firing treatment, the fired product is subjected to a vibration sieve and crushed to obtain a powder.

Table 1 shows the composition of the raw material mixture and the phase composition of the firing reaction product (composite powder) (crystal phase and its ratio).
Indicates. The composite compound powder is made of alkaline earth metal titanate (RTiO ₃ ) corresponding to the composition of the starting material mixture.
And octo-titanate (A _X M _Y Ti _8-Y O ₁₆ ) crystal phases are composed of composite particles having a phase constitution in which they are formed by complex precipitation. The particles have the same spherical shape as the granulated powder, and the average particle size is about 40 μm.

[0015]

[Table 1]

[0016]

[Reference Example] [Production of automobile brake disc pad and evaluation of friction characteristics] (1) Production of disc pad The composition shown in Table 2 was prepared and preformed according to a conventional method (pressing force: 15 MPa, time). (1 minute), and binding molding with a mold (pressing force: 15 MPa, temperature: 170 °C, time: 5 minutes), heat treatment (holding 3 hours at 180 °C), and polishing after demolding. Then, the test disk pads A to D are obtained. The disk pads A and B are the same as the base powder of the above-mentioned embodiment.
An example using No. 1 and No. 4 powders (average particle size: 40 μm), the disk pad C is a calcium titanate single phase powder (average particle size 40 μm), and the disk pad D is a calcium titanate single phase powder. This is an example in which a mixed powder of octotitanate single-phase powder (average particle size 40 μm) is used.

(2) Friction test A second efficacy test was carried out according to JASO C 406 "Passenger car braking system dynamometer test method". Initial braking speed...50km/
h, 100km/h, deceleration... 0.3G The test results are shown in the lower part of Table 2. The “face-to-face damage” is a comparison of the degree of abrasion damage on the surface of the mating material (material type: FC250) after the test by visual observation (○: extremely slight,
(Triangle: somewhat large, x: remarkable). The disc pads A and B using the composite compound powder of the present invention stably maintain a high friction coefficient μ as compared with the other disc pads C and E to be tested. In addition, the opponent's aggressiveness is also good.

[0018]

[Table 2]

[0019]

Industrial Applicability The composite titanium compound powder of the present invention has a particle structure in which different crystal phases of alkaline earth metal titanate crystal grains and octotitanate crystal grains are bonded to each other. It has material properties that cannot be obtained with mixed powders and is useful as an industrial material in various fields. For example, when applied to a friction material that constitutes a brake device for automobiles, etc., improved friction and wear characteristics such as high friction coefficient (μ), high wear resistance, and good face damage can be obtained. It is effective in reducing the size and weight and improving the durability and stability of the braking function.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masafumi Yasuda 1-1-1, Hama, Amagasaki-shi, Hyogo F-term in Kubota Technology Development Laboratory Co., Ltd. (reference) 3J058 BA67 BA68 BA73 EA37 FA01 GA22 GA26 GA31 GA41 GA64 GA65 GA68 GA82 GA92 4G047 CA06 CA07 CB04 CC03 CD03 CD07

Claims (2)

[Claims] 1. A general formula: RTiO ₃ [wherein R is selected from Mg, Ca _, Sr and Ba 1
Alkaline earth metal titanate crystal grains represented by one or two or more elements] and a general formula: A _X M _Y Ti _8-Y O ₁₆ [wherein A is selected from an alkali metal element and Ba] One or more elements, M is Al _, Fe, Cr _, Ga _, Mg _, Co _, Ni _, C
one or more elements selected from u _and Zn, X = 0.5 to 3, Y = X/2 (when M is a divalent element), Y = X (when M is a trivalent element) ] The composite titanium compound powder which consists of the composite crystal particle couple|bonded with the crystal particle of the hollandite type octotitanate represented by. 2. TiO ₂ or a titanium compound which produces TiO ₂ by heating, A ₂ O or an alkali metal compound which produces A ₂ O by heating, BaO or a barium compound which produces BaO by heating, RO or RO by heating. And alkaline earth metal compounds that produce
^* (MO ^* is MO or M ₂ O ₃ ) or an M element compound that produces MO ^* by heating is mixed at a compounding ratio according to the amount ratio of the crystal phase of the composite compound powder to be produced, and the mixed powder Granulate, and the temperature is 1300 to 1500
The method for producing a composite titanium compound powder according to claim 1, wherein the composite titanium compound powder is baked at a temperature of ℃.