CN106542809A

CN106542809A - Magnesia insulating ceramics

Info

Publication number: CN106542809A
Application number: CN201510606382.7A
Authority: CN
Inventors: 李征
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-09-22
Filing date: 2015-09-22
Publication date: 2017-03-29

Abstract

The invention discloses a kind of magnesia insulating ceramics, the various composition mass fraction of described a kind of magnesia insulating ceramics：Aluminium oxide AL2O3：20-25 parts；Carborundum SiC：10-18 parts；Burn Talcum：5-10 parts；SiO2：0.2-1.5 parts；CaCO3：10-20 parts；Suzhou soil：5-12 parts；Calcite：10-12 parts；Magnesite：12-15 parts；Li2O：5-15 parts；BaCO3：2-12 parts；V2O5：10-12 parts.

Description

Magnesia insulating ceramics

Technical field

The invention belongs to field of ceramic preparation technology, more particularly to a kind of magnesia insulating ceramics.

Background technology

Magnesia insulating ceramics is the ceramics with insulation function with aluminate and silicate containing MgO as principal crystalline phase.Magnesia insulating ceramics is widely used in HF radio set, such as radar, television set.Traditional ceramicses are compared with magnesia insulating ceramic materials, have following deficiency：1st, the dielectric loss of traditional ceramicses is high, and specific volume resistance is little, it is difficult to used as preferable iso lantite；2nd, the coefficient of expansion of traditional ceramicses is higher, and heat stability is bad, it is impossible to for wanting cube not vary with temperature in the insulant or thermo electric material of heat shock resistance；3rd, the ruggedness of traditional ceramicses material is poor, and manufacturing cost is higher.

Chinese patent 201310715168.6, a kind of entitled insulating ceramic materials and preparation method thereof, a kind of insulating ceramic materials include the following raw material counted by weight：Barium metatitanate.：10-15 parts, aluminium oxide：5-15 parts, silicon nitride：5-10 parts, Kaolin：15-20 parts, silica flour：2-6 parts, mass fraction are 20% sodium hydroxide solution 15-45 parts.As silica flour is with the addition of in ceramic material so that ceramic material insulating properties and wearability increase, and expand the application in ceramic material electronic product.Its deficiency is to the addition of silica flour so that manufacturing cost is greatly improved.

Chinese patent 201510022736.3, entitled the present invention relates to a kind of electric insulation ceramicses coating material, it includes crystalline phase highly resistant material and amorphous phase highly resistant material, by mass percentage, both consumptions are：Crystalline phase highly resistant material 12-36%, amorphous phase highly resistant material 64-88%, both consumptions meet absolutely；The crystalline phase of the crystalline phase highly resistant material is mainly Zn₂SiO₄、Zn₂Sb₂O₇、Zn₂VO₄、BiVO₄、Bi₂SiO₅、BaCrO₄, in the compositional system of the amorphous phase highly resistant material, include following component：SiO₂、Li₂O、K₂O, CaO etc..Electric insulation ceramicses coating material of the present invention can be with zinc oxide pressure-sensitive ceramic once-firing, firing range is at 1140-1220 DEG C, burn till rear coating surface bright and clean, do not absorb water, the good insulating protection performance of tool, its insulation resistivity can meet the anti-flashover requirement of zinc oxide varistor valve up to 3.3 × 1012 Ω cm.Its deficiency is that preparation process excessively complexity cannot be promoted on a large scale.

The content of the invention

In view of the shortcomings of the prior art, the present invention seeks to provide a kind of formula of magnesia insulating ceramics, it is to realize above-mentioned purpose of the invention, the present invention is adopted the following technical scheme that.

Magnesia insulating ceramics generally adopts CaO, MgO, SiO₂And transition metal and rare-earth oxide are additive.It can burn till at a lower temperature, typically contain 10% glass phase and paracrystalline phase in ceramic body in microstructure.In CaOAl₂O₃SiO₂In complex element, minimum congruent melting phase temperature is 1495.As SiO in porcelain composition₂When/CaO ratios are less than 2.16, it is anorthite and calcium hexaluminate with the mineral that corundum coexists；And work as SiO₂When/CaO ratios are more than 2.16, then corundum will be coexisted with mullite and anorthite.The advantage of magnesia insulating ceramics is that acid resistance is good, and in structure, crystal grain is tiny, but sintering temperature is than CaO-Al₂O₃-SiO₂It is higher tens degree, introduces rare earth oxide Y₂O₄, La₂O₃It is combined therewith, can further reduces sintering temperature.Lower several conventional additives of surface analysis and its main effect.

Clay：The purpose for adding clay is to increase plasticity and reduce sintering temperature, but excessively should not introducing.The 5%-10% of gross mass is accounted for typically.Because amount is more, the alkali metal ion brought into increases and irony is also more, not only so that ceramic material electric property deteriorates, but also sintering range can be made to narrow.

Alkaline-earth metal：Add a small amount of CaCO₃, SrCO₃And BaCO₃The insulating properties of ceramics, the wherein most pronounced effects of BaO can be changed, it can effectively improve two orders of magnitude of the volume of ceramic material and resistivity so that reduce 80%-90%.ScO takes second place, and CaO is worst.Due to alkaline earth oxide and Talcum, clay and other impurity production eutectics, accordingly, it is capable to sintering temperature is reduced, but content can reduce sintering range, wherein CaO most serious when high again, and SrO and BaO is a shade better.CaO also results in coarse grains, promotes ceramic body aging.Therefore the content in formula will be reduced.Additionally, BaCO₃Ceramic blank can also be prevented aging, but addition is advisable with 5%-10%, glass viscosity can be reduced more than 10%, reduce sintering range.The Free quartz that MgO can be decomposed with Talcum is combined, and produces the metasilicic acid magnesium of excellent electrical properties（MgOSiO₂）.Both unfavorable quartz had been eliminated, electrical property had been improve again, glass phase had been partially into, sintering temperature had been reduced, appropriate MgO can have expanded sintering range.In general formula, the addition of MgO is less than 8%, when more than 10%, it is possible to generate（2MgOSiO₂）Forsterite.Sintering temperature is not only increased, linear expansion coefficient is also add, heat stability is reduced.The introducing form of MgO is generally without the MgCO of pre-burning₃And magnesite.

The effect of aluminium oxide and similar, its sillimanite Al with Free quartz chemical combination generation function admirable of MgO₂O₃SiO₂。Al₂O₃Can also be with SiO₂Glass phase is proceeded to together in remove SiO₂, and do not reduce sintering temperature.Therefore it can prevent the aging of ceramic blank, improve and stablize the dielectric properties of ceramic material, but can significantly lower the rupture strength of ceramic material.Al₂O₃General consumption be 1%-3%.Addition can excessively generate the very long cordierite of electromechanical properties.Additionally, when being introduced with commercial alumina, it should be noted that mix homogeneously.

Borate is strong flux, can significantly reduce sintering temperature, but reduce the viscosity of glass also very greatly, 2% barium pyroborate is added such as in formula（BaO₂B₂O₃）, firing range only has 10-15 DEG C, and what borate was conventional has boracite（MgCIB₇O₁₇）And barium pyroborate.The latter is by BaCO₃Plus H₃BO₃Calcine and obtain.Boracite is the important solvent of metal and ceramic seal electrovacuum ceramic of compact base substrate.Therefore the MgCO of 1%-4% is added in formula₃, then performance is more excellent.

Zirconium oxide and Zinc Oxide can effectively expand the sintering range of material and improve the mechanical strength of material.Because they can improve the viscosity of glass phase, expand sintering range.And high-viscosity glass phase energy inhibiting grain growth, aplitic texture is formed, so as to improve mechanical strength.Their consumption is general no more than 4%, if consumption excessively occurs the second crystalline phase, increased the inhomogeneities of structure, reduces the quality of ceramic body.

In formula, add the Anhydrite of 6%-7%, sintering range expand 60 DEG C or so to.But contain alkali metal oxide in Anhydrite, greatly reduce the electrical property and mechanical performance of ceramic body, therefore strictly should control.Only use when the large complicated ceramic body not high to electrical performance demands is manufactured, because large size ceramic base substrate local temperature difference easily occurs when sintering, add Anhydrite to expanding sintering range, the rate of reducing the number of rejects and seconds is very effective.

The various composition mass fraction of described a kind of magnesia insulating ceramics：

Aluminium oxide AL₂O₃：20-25 parts；Carborundum SiC：10-18 parts；Burn Talcum：5-10 parts；SiO₂：0.2-1.5 parts；CaCO₃：10-20 parts；Suzhou soil：5-12 parts；Calcite：10-12 parts；Magnesite：12-15 parts；Li₂O：5-15 parts；BaCO₃：2-12 parts；V₂O₅：10-12 parts.

Specific embodiment

Embodiment 1：

Aluminium oxide AL₂O₃：22 parts；Carborundum SiC：12 parts；Burn Talcum：5 parts；SiO₂：1.2 part；CaCO₃：13 parts；Suzhou soil：8 parts；Calcite：10 parts；Magnesite：12 parts；Li₂O：12 parts；BaCO₃：8 parts；V₂O₅：10 parts.

Embodiment 2：

Aluminium oxide AL₂O₃：25 parts；Carborundum SiC：15 parts；Burn Talcum：6 parts；SiO₂：0.5 part；CaCO₃：15 parts；Suzhou soil：12 parts；Calcite：10 parts；Magnesite：15 parts；Li₂O：15 parts；BaCO3：5 parts；V₂O₅：10 parts.

Claims

1. magnesia insulating ceramics, it is characterised in that the element comprising following mass fraction： Aluminium oxide AL₂O₃：20-25 parts；Carborundum SiC：10-18 parts；Burn Talcum：5-10 parts；SiO₂：0.2-1.5 parts；CaCO₃：10-20 parts；Suzhou soil：5-12 parts；Calcite：10-12 parts；Magnesite：12-15 parts；Li2O：5-15 parts；BaCO₃：2-12 parts；V₂O₅：10-12 parts.