CN101386546B - Self-reacting alumina-base composite ceramic mold core for fine casting and preparation method thereof - Google Patents

Self-reacting alumina-base composite ceramic mold core for fine casting and preparation method thereof Download PDF

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Publication number
CN101386546B
CN101386546B CN 200810199121 CN200810199121A CN101386546B CN 101386546 B CN101386546 B CN 101386546B CN 200810199121 CN200810199121 CN 200810199121 CN 200810199121 A CN200810199121 A CN 200810199121A CN 101386546 B CN101386546 B CN 101386546B
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powder
composite ceramic
ceramic core
titanium dioxide
core
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CN101386546A (en
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覃业霞
邓飞其
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South China University of Technology SCUT
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South China University of Technology SCUT
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Abstract

The invention provides a self-reaction alumina-based composite ceramic core for precision casting, and a preparation method thereof. The composite ceramic core consists of alundum powder, in-situ synthesized aluminum titanate, MgTi2O5 and mullite. The composite ceramic core is prepared from the following raw materials in weight percentage: 70 to 85 percent of alundum powder with different particle sizes, 0 to 2 percent of magnesium oxide powder, 8 to 20 percent of titanium dioxide powder and 6 to 10 percent of kyanite powder, and carbon powder accounting for 1 to 3 percent of the gross mass of the four raw materials is added as an easy-breakdown agent. The method prepares the composite ceramic core through the following steps of mixing, dry-pressing, shaping and firing the raw materials at high temperature. As other raw materials are added to an alumina matrix of the invention, the prepared composite ceramic core has the advantages of good high-temperature chemical stability and thermal stability, low thermal expansion coefficient and small shrinkage factor after sintering, and meets the requirements of a ceramic core for precision casting on room temperature and high temperature strength.

Description

Self-reacting alumina-base composite ceramic mold core for fine casting and preparation method thereof
Technical field
The present invention relates to the refractory ceramic material field, be specifically related to a kind of precision casting and use ceramic core, be mainly used in and form the hollow lumen that internal combustion turbine of new generation efficiently cools off hollow blade.
Background technology
Modern aeroengine presses for the serviceability that improves gas turbine engine; It at first is the fuel gas temperature that improves turbine; It has determined the actual raising of the active power of PWR PLT, brings up to 1350 ℃ like fuel gas temperature from 1200 ℃, and rate of fuel consumption can reduce by 8%.A new generation's high-efficiency gas turbine turbine efficiently cools off hollow blade constantly to be developed; The cooling structure of blade develops into the present air cooling mode of efficiently dispersing by modes such as traditional convection current, backflow, impingement holes, air film coolings, and temperature will reach 1757 ℃ before the advanced at present engine turbine.
It is the same with routine casting that the moltening mold castings core removes, and surrounded by molten metal, working condition badly outside, effect with roasting also need stand to dewax.For this reason, core should satisfy following requirement: refractoriness is high, low, the dimensional stabilizing of coefficient of thermal expansion, and enough intensity, chemicalstability is good, is prone to remove.
Silica-based ceramic core is mainly used in the lower cylindrulite blade of casting and pouring temperature; When use temperature is higher than 1550 ℃ (for example single crystal casting); The silicon-base ceramic core high-temperature stability descends; Be easy to creep strain, and active element (Al, Hf, C) acutely is adsorbed in its surface in the alloy, and its application is restricted.Aluminum oxide (corundum) is the excellent high-temperature solid material, and its fusing point is up to 2054 ℃, and intensity is high, and chemicalstability is good, is a kind of very promising ceramic core body material.For the core of alumina base, because characteristics such as high refractoriness that aluminum oxide self had, high chemicalstability, thermostability make it as core performance guarantee is provided.
So far; External alumina based ceramic core can satisfy monocrystalline and eutectic pouring condition; The FSU just is applied to the produce single crystal hollow blade with alumina ceramic core from the seventies in 20th century, marches at the forefront of the world in the research and the application facet of alumina ceramic core.Though state such as English, U.S.A uses silica-based Tao Xin more in orientation and single crystal blade production, on the single crystal blade of complex thin-wall and eutectic blade, also used alumina ceramic core.
Some company's professional production ceramic cores have abroad been arranged now; Can supply military products and civilian goods production; Development through many decades; Its core product has formed specialization, appropriate scale of operation, and great variety of goods, best in quality, stable performances such as some raw and auxiliary materials that are associated, equipment are for the development of ceramic core provides superior external conditions.The operative norm that has possessed a whole set of from control with raw material, preparation technology, detection means and performance test everyway.Because the extensive intervention of computer is greatly improved complexity, precision and the smooth finish of ceramic core, in the production process parameters control more accurate, guaranteed high-level business-like ceramic core production.The application of various utility appliance such as laser core finishing machine has simultaneously greatly improved production efficiency and core qualification rate.In China, the development of alumina ceramic core is just at the early-stage in recent years, and except that indivedual aviation factory, most smart casting factory can't produce the precision casting with complicated inner cavity.Also do not occur commercial ceramic core supplier simultaneously, production unit is fairly simple, and processing parameter can not accurately be controlled, and its gap is conspicuous with abroad comparing.
The appearance of efficient air cooling blade will make the gordian technique that creates of core.Efficient air cooling blade is compared with traditional blades, and cooling structure is more complicated, the blade wall thickness is thinner.This will make the ME of core more complicated, and size is littler, and is higher to performance demands.For adapting to this variation, the composite ceramic core that research can be used under severe rugged environment more is imperative.Composite ceramics can improve breaking tenacity, fracture toughness property and resistance to elevated temperatures than the one-component pottery, and can reduce sintering temperature and high temperature amount of deflection, and the raising of these performances is highly beneficial to the ceramic core of complicated fine structure.
Summary of the invention
The objective of the invention is to overcome the above-mentioned deficiency that prior art exists; A kind of self-reacting alumina-base composite ceramic mold core for fine casting is provided; This composite ceramic core is applicable to that high-efficiency gas turbine turbine of new generation efficiently cools off the hollow blade precision casting, has high temperature resistant, stability at elevated temperature and phase stability is good, dimensional stability is high, shock-resistant, the advantage that is prone to remove.
Self-reacting alumina-base composite ceramic mold core for fine casting of the present invention; Form by lapis amiridis and original position synthetic aluminium titanates, two magnesium titanates and mullite; Said composite ceramic core is processed by following materials of weight proportions: varigrained lapis amiridis 70~85%, magnesia powder 0~2%, titanium dioxide powder 8~20%; Aquamaine stone flour 6~10%, and add account for these four kinds of raw material total masses 1~3% carbon dust as being prone to defeated and dispersed dose.
In the above-mentioned self-reacting alumina-base composite ceramic mold core for fine casting; The weight ratio of coarse grain, middle grain and particulate is in the said varigrained lapis amiridis: coarse grain: middle grain: particulate=1:2:1; Said coarse grain granularity is 200~800 μ m, and middle grain granularity is 7~25 μ m, and the particulate granularity is 0.5~6 μ m; And have the corundum powder that accounts for total lapis amiridis 1wt% at least, the particle mean sizes is at 0.75~3 μ m.
Alumina content is greater than 60wt% in the said aquamaine stone flour, Fe 2O 3Content is less than 1.5wt%, TiO 2Content is less than 2wt%, and the refractoriness of said aquamaine stone flour is higher than 1825 ℃.The ingredient requirement of said magnesia powder is: content of magnesia is greater than 98wt%, and the alkaline substance foreign matter content is less than 0.2wt%, and the magnesia powder granularity is less than 0.08mm.The ingredient requirement of said titanium dioxide powder is: content of titanium dioxide is greater than 99wt%, and the alkaline substance foreign matter content is less than 0.2wt%, and the titanium dioxide powder granularity is less than 0.05mm.
The present invention also provides the preparation method of above-mentioned self-reacting alumina-base composite ceramic mold core for fine casting, and its step is following:
(1) is that lapis amiridis at first mixes with said varigrained alumina substrate, adds in the mixing machinery together and mix with said magnesia powder, aquamaine stone flour, titanium dioxide powder, carbon dust then that the material after mixing is through dry pressing;
(2) above-mentioned shaping is good blank places the high temperature sintering furnace sintering; The process of heat temperature raising is the process that heats up continuously during sintering; Heat-up rate is controlled at 180~200 ℃/hour, is warming up to 1350~1550 ℃ and under this TR, be incubated 5~10 hours, then furnace cooling.
In the aforesaid method, the kyanite powder decomposes generation mullite and silicon-dioxide in the sintering process of step (2), and silicon-dioxide generates mullite through reaction in corundum powder again in the core sintering process; During the core sintering, corundum powder synthesizes aluminium titanates, two magnesium titanates second mutually with titanium dioxide powder, magnesia powder original position respectively.
Compared with prior art; The present invention has following advantage and effect: the alumina-based composite ceramics core that is proposed, utilize the aluminium titanates HMP, and approach the zero thermal expansion coefficient; Low thermal conductivity; The characteristics of advantages such as good thermal shock are utilized original position synthesis technique self synthetic two magnesium titanates identical with the aluminium titanates crystal formation in the core sintering process, and the good mullite of high-temperature behavior; The two decomposes with warm territory in the inhibition aluminium titanates through forming sosoloid with aluminium titanates, and satisfies the mechanical property of composite ceramic core.The present invention adds certain additive in alumina substrate; Can and obtain certain intensity at relatively low sintering temperature, improve the high temperature anti-thermal shock and the high temperature creep property of alumina-based composite ceramics core through aluminium titanates, the mullite of reaction in generation.The additive that the present invention is added in alumina substrate can reduce the sintering temperature of ceramic core, and in the sintering process original position synthetic these second can improve the alumina-based composite ceramics core mutually thermal shock resistance, high temperature creep property etc.Prepared ceramic core shrinking percentage is little, and room temperature and hot strength all satisfy the requirement of precision casting with ceramic core; Stability at elevated temperature and good thermal stability; Thermal expansivity is lower.Raw material in the proportioning raw materials provided by the invention does not almost have high temperature creep behind suitable sintering schedule sintering.
Embodiment
Below in conjunction with instance the present invention is further described.
Embodiment 1
Precision casting of the present invention is with original position borolon base composite ceramic core, and the feed proportioning weight percent consists of:
Lapis amiridis 85%, aquamaine stone flour 6%, magnesia powder 1%, titanium dioxide powder 8% add aforementioned base materials quality 2% carbon dust as being prone to defeated and dispersed dose.
Wherein lapis amiridis is by the different grain size proportioning: coarse grain: middle grain: the powder of particulate=1:2:1 is formed.
Different grain size proportioning lapis amiridis is mixed, and the back mixes with magnesia powder, titanium dioxide powder, aquamaine stone flour and carbon dust, under 1350~1550 ℃ of temperature, is incubated 5~10 hours behind the press forming, obtains ceramic core blank of the present invention behind the furnace cooling.
Saturated NaOH solution is boiled, be placed on ceramic core and wherein boil 1~3 hour, and be aided with high pressure water and dash, core is defeated and dispersed.
Embodiment 2
Precision casting of the present invention is with original position borolon base composite ceramic core, and the feed proportioning weight percent consists of:
Lapis amiridis 70%, aquamaine stone flour 10%, magnesia powder 0%, titanium dioxide powder 20% add aforementioned base materials quality 2% carbon dust as being prone to defeated and dispersed dose.
Wherein lapis amiridis is by the different grain size proportioning: coarse grain: middle grain: the powder of particulate=1:2:1 is formed.
Different grain size proportioning lapis amiridis is mixed, and the back mixes with magnesia powder, titanium dioxide powder, aquamaine stone flour and carbon dust, under 1350~1550 ℃ of temperature, is incubated 5~10 hours behind the press forming, obtains ceramic core blank of the present invention behind the furnace cooling.
Saturated NaOH solution is boiled, be placed on ceramic core and wherein boil 1~3 hour, and be aided with high pressure water and dash, core is defeated and dispersed.
Embodiment 3
Precision casting of the present invention is with original position borolon base composite ceramic core, and the feed proportioning weight percent consists of:
Lapis amiridis 75%, aquamaine stone flour 8%, magnesia powder 2%, titanium dioxide powder 15% add aforementioned base materials quality 2% carbon dust as being prone to defeated and dispersed dose.
Wherein lapis amiridis is by the different grain size proportioning: coarse grain: middle grain: the powder of particulate=1:2:1 is formed.
Different grain size proportioning lapis amiridis is mixed, and the back mixes with magnesia powder, titanium dioxide powder, aquamaine stone flour and carbon dust, under 1350~1550 ℃ of temperature, is incubated 5~10 hours behind the press forming, obtains ceramic core blank of the present invention behind the furnace cooling.
Saturated NaOH solution is boiled, be placed on ceramic core and wherein boil 1~3 hour, and be aided with high pressure water and dash, core is defeated and dispersed.
Embodiment 4
Precision casting of the present invention is with original position borolon base composite ceramic core, and the feed proportioning weight percent consists of:
Lapis amiridis 83.6%, aquamaine stone flour 7.6%, magnesia powder 0%, titanium dioxide powder 8.8% add aforementioned base materials quality 2% carbon dust as being prone to defeated and dispersed dose.
Wherein lapis amiridis is by the different grain size proportioning: coarse grain: middle grain: the powder of particulate=1:2:1 is formed.
Different grain size proportioning lapis amiridis is mixed, and the back mixes with magnesia powder, titanium dioxide powder, aquamaine stone flour and carbon dust, under 1350~1550 ℃ of temperature, is incubated 5~10 hours behind the press forming, obtains ceramic core blank of the present invention behind the furnace cooling.
Saturated NaOH solution is boiled, be placed on ceramic core and wherein boil 1~3 hour, and be aided with high pressure water and dash, core is defeated and dispersed.
Embodiment 5
Precision casting of the present invention is with original position borolon base composite ceramic core, and the feed proportioning weight percent consists of:
Lapis amiridis 73.6%, aquamaine stone flour 7.6%, magnesia powder 2%, titanium dioxide powder 16.8% add aforementioned base materials quality 2% carbon dust as being prone to defeated and dispersed dose.
Wherein lapis amiridis is by the different grain size proportioning: coarse grain: middle grain: the powder of particulate=1:2:1 is formed.
Different grain size proportioning lapis amiridis is mixed, and the back mixes with magnesia powder, titanium dioxide powder, aquamaine stone flour and carbon dust, under 1350~1550 ℃ of temperature, is incubated 5~10 hours behind the press forming, obtains ceramic core blank of the present invention behind the furnace cooling.
Saturated NaOH solution is boiled, be placed on ceramic core and wherein boil 1~3 hour, and be aided with high pressure water and dash, core is defeated and dispersed.

Claims (2)

1. self-reacting alumina-base composite ceramic mold core for fine casting; It is characterized in that: this composite ceramic core is made up of lapis amiridis and original position synthetic aluminium titanates, two magnesium titanates and mullite; Said composite ceramic core is processed by following materials of weight proportions: varigrained lapis amiridis 70~85%, magnesia powder 0~2%, titanium dioxide powder 8~20%; Aquamaine stone flour 6~10%;, and add account for these four kinds of raw material total masses 1~3% carbon dust as being prone to defeated and dispersed dose, the weight ratio of said magnesia powder is not 0; The weight ratio of coarse grain, middle grain and particulate is in the said varigrained lapis amiridis: coarse grain: middle grain: particulate=1: 2: 1; Said coarse grain granularity is 200~800 μ m; A middle grain granularity is 7~25 μ m; The particulate granularity is 0.5~6 μ m, and has the corundum powder that accounts for total lapis amiridis 1wt% at least, and the particle mean sizes is at 0.75~3 μ m; Alumina content is greater than 60wt% in the said aquamaine stone flour, Fe 2O 3Content is less than 1.5wt%, TiO 2Content is less than 2wt%, and the refractoriness of said aquamaine stone flour is higher than 1825 ℃; The ingredient requirement of said magnesia powder is: content of magnesia is greater than 98wt%, and the alkaline substance foreign matter content is less than 0.2wt%, and the magnesia powder granularity is less than 0.08mm; The ingredient requirement of said titanium dioxide powder is: content of titanium dioxide is greater than 99wt%, and the alkaline substance foreign matter content is less than 0.2wt%, and the titanium dioxide powder granularity is less than 0.05mm; Said composite ceramic core is made by following steps:
(1) said different grain size lapis amiridis is at first mixed, add in the mixing machinery together and mix with said magnesia powder, aquamaine stone flour, titanium dioxide powder, carbon dust then, the material after mixing is through dry pressing;
(2) above-mentioned shaping is good blank places the high temperature sintering furnace sintering; The process of heat temperature raising is the process that heats up continuously during sintering; Heat-up rate is controlled at 180~200 ℃/hour, is warming up to 1350~1550 ℃ and under this TR, be incubated 5~10 hours, then furnace cooling.
2. the preparation method of the described self-reacting alumina-base composite ceramic mold core for fine casting of claim 1 is characterized in that comprising the steps:
(1) said different grain size lapis amiridis is at first mixed, add in the mixing machinery together and mix with said magnesia powder, aquamaine stone flour, titanium dioxide powder, carbon dust then, the material after mixing is through dry pressing;
(2) above-mentioned shaping is good blank places the high temperature sintering furnace sintering; The process of heat temperature raising is the process that heats up continuously during sintering; Heat-up rate is controlled at 180~200 ℃/hour, is warming up to 1350~1550 ℃ and under this TR, be incubated 5~10 hours, then furnace cooling.
CN 200810199121 2008-10-14 2008-10-14 Self-reacting alumina-base composite ceramic mold core for fine casting and preparation method thereof Expired - Fee Related CN101386546B (en)

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CN103231021B (en) * 2011-12-13 2015-06-17 江苏图南合金股份有限公司 Alumina-based ceramic core and preparation method thereof
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