CN1142478A

CN1142478A - Composite ceramics and production thereof

Info

Publication number: CN1142478A
Application number: CN 95111718
Authority: CN
Inventors: 王佩玲; 王浩; 孙维莹; 庄汉锐; 严东生
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 1995-08-04
Filing date: 1995-08-04
Publication date: 1997-02-12
Anticipated expiration: 2015-08-04
Also published as: CN1062542C

Abstract

A complex-phase ceramic features its high-temp (1350 deg.C) strength can reach 500-715 MPa. The m and n values in alpha's formula: Ym/3Si12-(m+n)AlM=NOnN16-n are used as main parameters to design contents of alpha and beta as primary crystal phases. When m=0.3 and n=0.1, the content of YAG as intercrystalline phase is 9% of primary crystal phase weight. Its preparing process includes proportioning, single-axial shaping under 20 MPa, cold isostatic press shaping under 200 MPa, and non-pressure sinter for 2 hr at 1800 deg.C in N2 flow or sinter at 1900-2000 deg.C for 1.5-3 hr in 1.5 MPa of N2. Its embedding powder is Si3N4, AIN and BN (6:3:1 in wt.%).

Description

Composite ceramics and preparation method

What the present invention relates to is a kind of high strength with excellent high mechanical property of not having pressure and the preparation of high nitrogen pressure sintering process, and grand (Sialon) complex phase ceramic of high rigidity match belongs to the silicon nitride-based material field.

Sialon is Si ₃N ₄Sosoloid, Si is at first proposed in 1978 by people such as K.H.Jack ₃N ₄α-Si is arranged ₃N ₄And β-Si ₃N ₄Two kinds of variant are called α-Sialon (being called for short α ') and beta-Sialon (being called for short β ') with their isostructural sosoloid, with Si ₃N ₄The same, the grain morphology and the performance of these sosoloid have their own characteristics each, and be each has something to recommend him.For example: α ' has high rigidity and good heat-shock resistance, β ' has high intensity and high fracture toughness property, the Sialon complex phase ceramic that α ' and β ' are formed can be learnt from other's strong points to offset one's weaknesses both and be formed the Sialon complex phase ceramic that has high rigidity concurrently and high strength (especially intensity under the high temperature) is arranged, and is the purpose that the ceramist pursues for it always.

Yet, because Si ₃N ₄Material is the very strong material of covalent linkage, thereby causes being difficult to sintering densification, often adds metal oxide such as La in sintering process ₂O ₃, Y ₂O ₃, Al ₂O ₃As additive, and make ceramic densifying by the approach of liquid phase sintering.It's a pity that liquid phase is present in the crystal boundary of pottery with the form of glassy phase in process of cooling, influenced ceramic mechanical behavior under high temperature and limited range of application thereby the glassy phase softening temperature is low.

The objective of the invention is to use existing Y, Si, Al, O, N quinary system facies relationship knowledge, seek out component zone, do not press sintering process to prepare the composite ceramics of excellent property with having pressure and high nitrogen with good sintering character.

The objective of the invention is by with high-melting-point YAG (Y ₃Al ₅O ₁₂) be the crystal boundary phase, utilize α ' and β ' to have high rigidity and high-intensity advantage respectively and do not press and the Sialon complex phase ceramic of high nitrogen pressure technology preparation implements to have.

Specifically:

(1) with the general formula of α ': Y _M/3Si _12-(m+n)Al _M+nO _nN _16-nIn m, n value as the significant parameter of design Sialon complex phase ceramic principal crystalline phase α ' and β ' content, work as m=0.3, n=1.0 obtains α ': β ' ≈ 50: 50 (fluctuation range 40: 60).Fig. 1-1 is β-Si ₃N ₄-β ₁₀(Si _5.2Al _0.8O _0.8N _7.2)-α-Sialon (m=1.0, n=1.7)-position (photomechanical printing part) of YAG consistency tetrahedron in whole Y, Si, Al/O, N quinary system (rib dimension body), Fig. 1-2 amplifies diagram for it.

(2) coking property of α ' and β ' complex phase ceramic depends on YAG (Y in the original component ₃Al ₅O ₁₂) content, the content that the present invention controls YAG is 9% of principal crystalline phase weight, YAG is the crystal boundary phase.

⑶ after starting powder is formed the proportioning weighing by above-mentioned (1), (2), at Al ₂O ₃Be dispersion medium with the dehydrated alcohol in the ball milling bucket, Si ₃N ₄Ball is that ball-milling medium mixed 24 hours, take out the slip oven dry after, sieve through 75 eye mesh screens, at 20MPa uniaxial tension compacted under after the 200MPa isostatic cool pressing is made biscuit.

(4) biscuit is at 1800 ℃ of 1 normal atmosphere N ₂Pressureless sintering under the air-flow is incubated 2 hours, and it is Si that powder is buried in pressureless sintering ₃N ₄: AlN: BN=6: 3: 1 (wt%) or depressing under 1900-2000 ℃ of temperature 1.5-3.0 hour sintering of insulation at the high nitrogen of 1.5MPa again after the pressureless sintering.

(5) burn till sample all at 1350 ℃ of logical N ₂24 hours crystallization of thermal treatment are handled under the condition.

Advantage of the present invention is:

(1) α ' is close with β ' content in the principal crystalline phase, and the agglomerating complex phase ceramic has high strength and high rigidity concurrently.

(2) because with high-melting-point YAG crystal boundary phase, so material also has excellent high-temperature mechanical property (seeing embodiment 1-5 for details).

(3) can help suitability for industrialized production there not being the Sialon complex phase ceramic that obtains densification under pressure and the high nitrogen compression technology condition.

Embodiment 1

Si with Ube product company production newly ₃N ₄(UBE-10) be Si ₃N ₄Raw material, AlN, Al ₂O ₃, Y ₂O ₃The purity of powder is 99.9%, average particle size particle size 1-2 μ, and consider Si ₃N ₄With the oxygen level of nitrogenous particle surfaces such as AlN, press m=0.3, n=1.0, YAG weight is that 9% of principal crystalline phase weight is prepared burden, biscuit is at 1800 ℃, under 1 normal atmosphere flowing nitrogen, pressureless sintering 2 hours, burying powder is Si ₃N ₄: AlN: BN=6: 3: 1 (wt%), burn till behind the sample in 1350 ℃ of logical N ₂Following 24 hours crystallization of condition are handled.The room temperature strength of sample is 612MPa, and fracture toughness property is 3.9 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1594, the intensity in the time of its 1000 ℃ is 595MPa, the intensity in the time of 1350 ℃ is 500MPa.

Embodiment 2

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1800 ℃ of 1 normal atmosphere flowing nitrogens, be incubated 2h, depress with 1900 ℃ of insulations 1.5 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 840MPa, and fracture toughness property is 6.1 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1820, the intensity in the time of its 1000 ℃ is 740MPa, the intensity in the time of 1350 ℃ is 620MPa.

Embodiment 3

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h with 1800 ℃, depress with 1900 ℃ of insulations 3.0 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 890MPa, and fracture toughness property is 6.9 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1850, the intensity in the time of its 1000 ℃ is 780MPa, the intensity in the time of 1350 ℃ is 660MPa.

Embodiment 4

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h with 1800 ℃, depress with 1950 ℃ of insulations 1.5 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 860MPa, and fracture toughness property is 6.5 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1820, the intensity in the time of its 1000 ℃ is 775MPa, the intensity in the time of 1350 ℃ is 650MPa.

Embodiment 5

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h with 1800 ℃, depress with 2000 ℃ of insulations 1.5 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 925MPa, and fracture toughness property is 7.2 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1884, the intensity in the time of its 1000 ℃ is 830MPa, the intensity in the time of 1350 ℃ is 715MPa.

Claims

1. a composite ceramics is made up of Y, Si, Al, O, N quinary system, it is characterized in that

(1) with the general formula Y of α ' _M/3Si _12-(m+n)Al _M+nO _nN _16-nIn m, n value as the significant parameter of design composite ceramics principal crystalline phase α ', β ' content;

(2) m=0.3, during n=1.0, α ': β ' ≈ 50: 50, fluctuation range is 40: 60;

(3) crystal boundary phase YAG (Y ₃Al ₅O ₁₂) content be 9% of principal crystalline phase weight.

2. by the preparation method of the described composite ceramics of claim 1, it is characterized in that:

(1) press principal crystalline phase α ': β ' ≈ 50, the content of crystal boundary phase YAG are 9% batching of principal crystalline phase weight;

(2) in the ball milling bucket, be dispersion medium with the dehydrated alcohol, Si ₃N ₄Ball is that ball-milling medium mixed 24 hours, and oven dry is sieved, at 20MPa uniaxial tension moulding 200MPa cold isostatic compaction then;

(3) biscuit is at 1800 ℃ of 1 normal atmosphere N ₂The pressureless sintering insulation is 2 hours under the air-flow, and burying powder is Si ₃N ₄: AlN: BN=6: 3: 1 (wt%) or depressing under 1900-2000 ℃ of temperature insulation 1.5-3.0 hour at the high nitrogen of 1.5MPa again after the pressureless sintering;

(4) sample burns till the back in 1350 ℃ of logical N ₂Following 24 hours crystallization of condition are handled.

3. by the preparation method of the described composite ceramics of claim 2, it is characterized in that 1800 ℃ of 1 normal atmosphere N ₂After air-flow is incubated pressureless sintering in 2 hours down, depress with 1.5 hours sintering of 1900 ℃ of insulations at the high nitrogen of 1.5MPa.

4. by the preparation method of the described composite ceramics of claim 2, it is characterized in that 1800 ℃ of 1 normal atmosphere N ₂After air-flow is incubated pressureless sintering in 2 hours down, depress with 3 hours sintering of 1900 ℃ of insulations at the high nitrogen of 1.5MPa.

5. by the preparation method of the described composite ceramics of claim 2, it is characterized in that pressureless sintering after, depress with 1.5 hours sintering of 1950 ℃ of insulations at the high nitrogen of 1.5MPa.

6. by the preparation method of the described composite ceramics of claim 2, it is characterized in that pressureless sintering after, depress with 1.5 hours sintering of 2000 ℃ of insulations at the high nitrogen of 1.5MPa.