CN103803973A - Compact pure-phase lanthanum zirconate ceramic with low thermal conductivity and high strength, and preparation method thereof - Google Patents
Compact pure-phase lanthanum zirconate ceramic with low thermal conductivity and high strength, and preparation method thereof Download PDFInfo
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- CN103803973A CN103803973A CN201310730564.6A CN201310730564A CN103803973A CN 103803973 A CN103803973 A CN 103803973A CN 201310730564 A CN201310730564 A CN 201310730564A CN 103803973 A CN103803973 A CN 103803973A
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Abstract
The invention discloses compact pure-phase lanthanum zirconate ceramic with low thermal conductivity and high strength, and a preparation method thereof. A chemical formula of the lanthanum zirconate ceramic is La2Zr2O7, the compactness is greater than 85%, the compression strength is 310-500MPa, the thermal conductivity and the thermal diffusion coefficient at normal temperature respectively are 1.55-1.79W/(m.K) and (0.90-0.76)*10<-6>m<2>/s; the thermal conductivity and the thermal diffusion coefficient at the temperature of 1200 DEG C respectively are 0.75-0.94W/(m.K) and (0.35-0.45)*10<-6>m<2>/s; the breaking tenacity is 1.45-1.70MPa. The lanthanum zirconate ceramic prepared according to the lanthanum zirconate ceramic preparation method provided by the invention has the advantages of low thermal conductivity, high melting point, good inoxidizability, excellent mechanical property, good high temperature-phase stability and the like, and the requirements of hypersonic velocity aerospace vehicles on the performances of high-strength thermal insulation ceramic materials can be met.
Description
Technical field
The present invention relates to technical field of ceramic material, in particular to a kind of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery and preparation method thereof.
Background technology
Along with the development of aeronautical and space technology, more and more serious to the heat effect of body by pneumatic generation heat when aircraft is in running order, such as the temperature of wing or empennage leading edge is up to 1455 ℃.Thermal protection system thickness direction at aircraft can produce very large thermograde, because the material properties of aircraft web member and thermal protection shield differs larger, makes to produce in different layers the heat bridge phenomenon of temperature distributing disproportionation.This can cause the Stiffness of housing construction, and produces thermal stresses in housing construction material, even material ablation, and then have a strong impact on the dynamics of housing construction, increase the potential safety hazard of aircraft.In order to overcome extreme thermal environment and harsh loading condition, aerospace must possess the performances such as high-melting-point, low thermal conductance, high-temperature-phase stability, high elastic coefficient and high strength, good anti-oxidant and erosion resistance with heat bridge blocking-up system material.
The research that possesses the thermally protective materials of many performances based on exploitation mainly concentrates on thermal insulation ceramics material.Wherein, ZrO
2pottery has the premium propertiess such as high-melting-point, lower thermal conductivity, high thermal expansion coefficient, becomes the primary selection of ceramic insulation protective layer material, is also the most ripe current through engineering approaches lagging material.But, pure ZrO
2material, at 1170 ℃ of crystal conversions that can occur from monoclinic phase to Tetragonal, can be accompanied by 4 ~ 6% volume change simultaneously, and in Thermal Cycling, pottery is inner can produce very large stress concentration, thereby causes the generation of tiny crack, makes e protective layer lose the effection.By at ZrO
2in add stablizer to stop its crystal conversion, improved its thermostability, but be limited to 950 ℃ in its working temperature, be difficult to meet to the more requirement of high workload envrionment temperature.Meanwhile, complete fully dense yttrium-stabile zirconium dioxide (YSZ) material is too high in the thermal conductivity of hot conditions, is difficult to play thermal insulation protection effect.Such as, YSZ thermal conductivity at 1000 ℃ is 2.3 W/ (mK), this numerical value is still aobvious higher.
In order to develop, performance is more excellent, service condition is harsher, can substitute the novel material system of the YSZ material of current comparative maturity, at present both at home and abroad respectively at rare earth zirconate (Ln
2zr
2o
7), garnet (Y
3al
xfe
5 ~ xo
12), alkaline earth metal zirconate (SrZrO
3and BaZrO
3), hexaplanar lanthanum aluminate (LaAl
11o
19, be called for short lanthanum hexaaluminate) and lanthanum orthophosphate (LaPO
4) etc. system conduct a research.
Wherein, zirconic acid lanthanum pottery fusing point is high, and resistance of oxidation is strong, has two kinds of structures of orderly pyrrhite and unordered fluorite, but due to La
3+with Zr
4+radius ratio larger, La
2zr
2o
7while there is order-disorder(phase)transition, needed energy is larger, therefore La
2zr
2o
7before reaching fusing point, can not undergo phase transition, be single pyrochlore structure, shows very good structure thermal stability.And the crystalline structure of zirconic acid lanthanum can effectively strengthen phon scattering, therefore this material also has lower thermal conductivity, has good heat-proof quality.In terms of mechanics, zirconic acid lanthanum stupalith has high rigidity, high strength, high elastic coefficient, a series of good mechanical properties such as wear-resistant.At present, the research of preparing zirconic acid lanthanum thermal barrier coating as main method take plasma body, physical vapor deposition is more, and it is relatively less to be absorbed in the fine and close thermal insulation ceramics preparation technology's of zirconic acid lanthanum the exploitation of heat bridge blocking-up use.The present invention focuses on the research of preparation technology, calorifics and the mechanical property of zirconic acid lanthanum pottery, and making zirconic acid lanthanum pottery become the novel heat bridge blocking-up thermal insulation ceramics of a kind of structure becomes possibility, has important value.
Summary of the invention
The object of the invention is to overcome the deficiency that existing high temperature insulating material thermal conductivity and mechanical strength are difficult to meet actual needs, a kind of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery and preparation method thereof are provided.
The chemical formula of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery is La
2zr
2o
7, be the green stone crystalline phase of single Jiao, density is greater than 85%, and compressive strength is 310 ~ 500MPa, and normal temperature thermal conductivity and thermal diffusivity are respectively 1.55 ~ 1.79W/ (mK), (0.90 ~ 0.76) × 10
-6m
2/ s, 1200 ℃ of thermal conductivities and thermal diffusivity are respectively 0.75 ~ 0.94W/ (mK), (0.35 ~ 0.45) × 10
-6m
2/ s, fracture toughness property is 1.45 ~ 1.70MPa.
The preparation method's of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery step is as follows:
1) lanthanum nitrate that is 0.1 ~ 1mol/l by concentration and the aqueous solution of basic zirconium chloride also stir 0.5 ~ 1h, form La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammoniacal liquor with the speed of 10 ~ 60ml/min, dropping finishes rear continuation and stirs still aging 12 ~ 24h after 0.5 ~ 2h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, by deionized water wash, separation for throw out, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 80 ~ 110 ℃, dry 12 ~ 24h, obtains amorphous powder;
2) by amorphous powder ball milling 1 ~ 3h, thermal treatment 3 ~ 6h under 400 ~ 1100 ℃ of conditions, ball milling 3 ~ 8h again, screening obtains the submicron powder that median size is 300 ~ 900nm, add 3 ~ 8% polyvinyl alcohol solution granulation of submicron powder quality, in polyvinyl alcohol solution, the mass percent of polyvinyl alcohol is 5%, at 60 ~ 120 ℃, dry to polyvinyl alcohol solution content and account for 1 ~ 3% of submicron powder quality, slowly be forced into 200 ~ 300MPa pressurize 1 ~ 5min, the dry-pressing formed biscuit that makes, biscuit is carried out under 100 ~ 200MPa pressure to isostatic cool pressing processing 0.5 ~ 3min and make zirconic acid lanthanum biscuit of ceramics,
3) zirconic acid lanthanum biscuit of ceramics is warming up to 80 ~ 120 ℃ of insulation 0.5 ~ 1.5h with 3 ~ 10 ℃/min speed, then be warming up to 400 ~ 600 ℃ of insulation 1 ~ 3h with 3 ~ 10 ℃/min speed, further be warming up to 1400 ~ 1600 ℃ of insulation 4 ~ 10h with 5 ~ 10 ℃/min speed again, finally be cooled to normal temperature with 5 ~ 10 ℃/min speed, obtain lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery.
The advantage that the present invention has and positively effect:
1) technique is simple: adopt dry-pressing formed-normal pressure-sintered legal system for zirconic acid lanthanum pottery, equipment requirements is low, and product cost is low;
2) high-compactness: the density of zirconic acid lanthanum pottery is greater than 85%;
3) good thermal property: normal temperature thermal conductivity and thermal diffusivity are respectively 1.55 ~ 1.79W/ (mK), (0.90 ~ 0.76) × 10
-6m
2/ s, 1200 ℃ of thermal conductivities and thermal diffusivity are respectively 0.75 ~ 0.94W/ (mK), (0.35 ~ 0.45) × 10
-6m
2/ s, at high temperature has good heat-proof quality, is much better than ZrO
2the heat-proof quality of thermal insulation ceramics;
4) excellent mechanical performances: compressive strength is 310 ~ 500MPa, fracture toughness property is 1.45 ~ 1.7MPa.Under complicated thermal environment, can carry larger load, long service life;
5) good stability: be stable pyrochlore structure in ℃ use range of room temperature ~ 1600, without phase transformation.
Lower thermal conductivity provided by the invention, high strength dense pure phase zirconic acid lanthanum ceramic preparation are by processing the early stages such as zirconic acid lanthanum powder preparation, ball milling, thermal treatment and ball milling screening, in conjunction with follow-up granulation, dry-pressing formed, cold isostatic compaction and high-sintering process, prepare fine and close pure phase zirconic acid lanthanum pottery.Described preparation method is simple, can realize industrialization in batches and produce.The zirconic acid lanthanum pottery of preparation has good calorifics, mechanical property and thermostability, can meet aerospace craft requirement to material heat-proof quality and mechanics load-carrying properties under complicated thermal environment.
Accompanying drawing explanation
Fig. 1 be lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery preparation method process flow sheet;
The transmission electron microscope picture that Fig. 2 (a) is the zirconic acid lanthanum pottery amorphous powder that provides in embodiments of the invention 2;
The transmission electron microscope picture of the powder that Fig. 2 (b) obtains for the zirconic acid lanthanum pottery amorphous powder providing in embodiments of the invention 2 after 900 ℃ of thermal treatment 4h;
The transmission electron microscope picture of the powder that Fig. 2 (c) obtains for the zirconic acid lanthanum pottery amorphous powder providing in embodiments of the invention 4 after 1000 ℃ of thermal treatment 4h;
The surface sweeping Electronic Speculum figure that Fig. 3 is the zirconic acid lanthanum ceramics sample that provides in embodiments of the invention 1;
Fig. 4 is the XRD figure spectrum of the zirconic acid lanthanum ceramics sample that in embodiments of the invention 1,2,5, at 1500 ℃, 1600 ℃, 1400 ℃ temperature prepared by sintering respectively.
Embodiment
For above-mentioned feature and advantage of the present invention can be become apparent, special embodiment below, and coordinate institute's accompanying drawing to elaborate.
The chemical formula of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery is La
2zr
2o
7, be the green stone crystalline phase of single Jiao, the density of pottery is greater than 85%, and compressive strength is 310 ~ 500MPa, and normal temperature thermal conductivity and thermal diffusivity are respectively 1.55 ~ 1.79W/ (mK), (0.90 ~ 0.76) × 10
-6m
2/ s, 1200 ℃ of thermal conductivities and thermal diffusivity are respectively 0.75 ~ 0.94W/ (mK), (0.35 ~ 0.45) × 10
-6m
2/ s, fracture toughness property is 1.45 ~ 1.70MPa.
As shown in Figure 1, the preparation method's of lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery step is as follows:
1) lanthanum nitrate that is 0.1 ~ 1mol/L by concentration and the aqueous solution of basic zirconium chloride also stir 0.5 ~ 1h, form La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammoniacal liquor with the speed of 10 ~ 60ml/min, dropping finishes rear continuation and stirs still aging 12 ~ 24h after 0.5 ~ 2h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, by deionized water wash, separation for throw out, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 80 ~ 110 ℃, dry 12 ~ 24h, obtains amorphous powder;
2) by amorphous powder ball milling 1 ~ 3h, thermal treatment 3 ~ 6h under 400 ~ 1100 ℃ of conditions, ball milling 3 ~ 8h again, screening obtains the submicron powder that median size is 300 ~ 900nm, add 3 ~ 8% polyvinyl alcohol solution granulation of submicron powder quality, in polyvinyl alcohol solution, the mass percent of polyvinyl alcohol is 5%, at 60 ~ 120 ℃, dry to polyvinyl alcohol solution content and account for 1 ~ 3% of submicron powder quality, slowly be forced into 200 ~ 300MPa pressurize 1 ~ 5min, the dry-pressing formed biscuit that makes, biscuit is carried out under 100 ~ 200MPa pressure to isostatic cool pressing processing 0.5 ~ 3min and make zirconic acid lanthanum biscuit of ceramics,
3) zirconic acid lanthanum biscuit of ceramics is warming up to 80 ~ 120 ℃ of insulation 0.5 ~ 1.5h with 3 ~ 10 ℃/min speed, then be warming up to 400 ~ 600 ℃ of insulation 1 ~ 3h with 3 ~ 10 ℃/min speed, further be warming up to 1400 ~ 1600 ℃ of insulation 4 ~ 10h with 5 ~ 10 ℃/min speed again, finally be cooled to normal temperature with 5 ~ 10 ℃/min speed, obtain lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery.
Below in conjunction with specific embodiments described preparation method is further described and is explained.
1) lanthanum nitrate that is 0.1mol/L by concentration and the aqueous solution of basic zirconium chloride also stir 1h, form La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 10ml/min, dropping finishes rear continuation and stirs still aging 24h after 2h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 80 ℃ of temperature, dry 24h, obtains amorphous powder;
2) by amorphous powder ball milling 3h, thermal treatment 5h under 700 ℃ of conditions, ball milling 8h again, screening is processed and is obtained the submicron powder that median size is 300nm, add 8% polyvinyl alcohol solution granulation of submicron powder quality, in polyvinyl alcohol solution, the mass percent of polyvinyl alcohol is 5%, at 60 ℃ of temperature, dry to polyvinyl alcohol solution and account for 3% of submicron powder quality, dry-pressing formed under 300MPa pressure, slowly be forced into highest pressure and pressurize 5min makes biscuit, biscuit is carried out under 200MPa pressure to isostatic cool pressing processing 3min and make zirconic acid lanthanum biscuit of ceramics,
3) zirconic acid lanthanum biscuit of ceramics is warming up to 80 ℃ of insulation 1.5h with 3 ℃/min speed, then be warming up to 500 ℃ of insulation 3h with 3 ℃/min speed, further be warming up to 1500 ℃ of insulation 6h with 5 ℃/min speed again, be finally cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Draw through correlated performance Measurement and Computation, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 94.5%, compressive strength is 500MPa, and thermal conductivity and thermal diffusivity are respectively 1.79 ~ 0.94W/ (mK), (0.90 ~ 0.45) × 10 from normal temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.70 MPa.
1) concentration be respectively to the lanthanum nitrate of 0.3mol/L and the aqueous solution of basic zirconium chloride and stir 1h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 20ml/min, dropping finishes rear continuation and stirs still aging 20h after 1.5h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 100 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 2.5h, thermal treatment 4h under 900 ℃ of conditions, ball milling 6h again, screening is processed and is obtained the submicron powder that median size is 400nm, add 7% polyvinyl alcohol solution granulation of submicron powder quality, at 90 ℃ of temperature, dry to polyvinyl alcohol solution amount and account for 2.5% of submicron powder quality, dry-pressing formed under 260MPa pressure, slowly be forced into highest pressure and pressurize 3min makes biscuit, biscuit carried out under 140MPa pressure to isostatic cool pressing and process 2min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 100 ℃ of insulation 1.5h with 5 ℃/min speed, then be warming up to 500 ℃ of insulation 2.5h with 5 ℃/min speed, further be warming up to 1600 ℃ of insulation 5h with 10 ℃/min speed again, finally be cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 92.1%, compressive strength is 421MPa, and thermal conductivity and thermal diffusivity are respectively 1.72 ~ 0.87 W/ (mK), (0.85 ~ 0.42) × 10 from room temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.62 MPa.
Embodiment 3
1) concentration be respectively to the lanthanum nitrate of 0.4mol/L and the aqueous solution of basic zirconium chloride and stir 1h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 30ml/min, dropping finishes rear continuation and stirs still aging 15h after 1h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 100 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 2.5h, thermal treatment 4h under 750 ℃ of conditions, ball milling 5h again, screening is processed and is obtained the submicron powder that median size is 350nm, add 7% polyvinyl alcohol solution granulation of submicron powder quality, at 90 ℃ of temperature, dry to polyvinyl alcohol solution content and account for 2% of submicron powder quality, dry-pressing formed under 250MPa pressure, slowly be forced into highest pressure and pressurize 2min makes biscuit, biscuit carried out under 130MPa pressure to isostatic cool pressing and process 1.5min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 100 ℃ of insulation 1h with 3 ℃/min speed, then be warming up to 550 ℃ of insulation 2.5h with 5 ℃/min speed, further be warming up to 1550 ℃ of insulation 6h with 10 ℃/min speed again, finally be cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 92.4%, compressive strength is 447MPa, and thermal conductivity and thermal diffusivity are from room temperature to 1200 ℃ variation tendency 1.74 ~ 0.89W/ (mK), (0.86 ~ 0.43) × 10 respectively
-6m
2/ s, fracture toughness property is 1.61MPa.
Embodiment 4
1) concentration be respectively to the lanthanum nitrate of 0.5mol/L and the aqueous solution of basic zirconium chloride and stir 1h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 30ml/min, dropping finishes rear continuation and stirs still aging 15h after 1h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 110 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 2h, thermal treatment 4h under 1000 ℃ of conditions, ball milling 5h again, screening is processed and is obtained the submicron powder that median size is 550nm, add 6% polyvinyl alcohol solution granulation of submicron powder quality, at 100 ℃ of temperature, dry to polyvinyl alcohol solution content and account for 2% of submicron powder quality, dry-pressing formed under 240MPa pressure, slowly be forced into highest pressure and pressurize 3min makes biscuit, biscuit carried out under 130MPa pressure to isostatic cool pressing and process 1min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 100 ℃ of insulation 1h with 8 ℃/min speed, then be warming up to 500 ℃ of insulation 2.5h with 10 ℃/min speed, further be warming up to 1450 ℃ of insulation 8h with 10 ℃/min speed again, finally be cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 91.5%, compressive strength is 392MPa, and thermal conductivity and thermal diffusivity are respectively 1.65 ~ 0.82 W/ (mK), (0.83 ~ 0.39) × 10 from room temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.57MPa.
Embodiment 5
1) concentration be respectively to the lanthanum nitrate of 1mol/L and the aqueous solution of basic zirconium chloride and stir 1h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 20ml/min, dropping finishes rear continuation and stirs still aging 12h after 1h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 110 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 2h, thermal treatment 3h under 1100 ℃ of conditions, ball milling 4h again, screening is processed and is obtained the submicron powder that median size is 700nm, add 6% polyvinyl alcohol solution granulation of submicron powder quality, at 120 ℃ of temperature, dry to polyvinyl alcohol solution content and account for 1.5% of submicron powder quality, dry-pressing formed under 230MPa pressure, slowly be forced into highest pressure and pressurize 3min makes biscuit, biscuit carried out under 100MPa pressure to isostatic cool pressing and process 1min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 100 ℃ of insulation 1.5h with 10 ℃/min speed, then be warming up to 500 ℃ of insulation 2h with 10 ℃/min speed, further be warming up to 1400 ℃ of insulation 10h with 10 ℃/min speed again, finally be cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 90.6%, compressive strength is 367MPa, and thermal conductivity and thermal diffusivity are respectively 1.61 ~ 0.79 W/ (mK), (0.80 ~ 0.38) × 10 from room temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.53MPa.
Embodiment 6
1) concentration be respectively to the lanthanum nitrate of 0.5mol/L and the aqueous solution of basic zirconium chloride and stir 1h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 50ml/min, dropping finishes rear continuation and stirs still aging 24h after 1h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 110 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 2h, thermal treatment 5h under 550 ℃ of conditions, ball milling 3h again, screening is processed and is obtained the submicron powder that median size is 850nm, add 5% polyvinyl alcohol solution granulation of submicron powder quality, at 80 ℃ of temperature, dry to polyvinyl alcohol solution content and account for 2% of submicron powder quality, dry-pressing formed under 300MPa pressure, slowly be forced into highest pressure and pressurize 3min makes biscuit, biscuit carried out under 150MPa pressure to isostatic cool pressing and process 1min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 120 ℃ of insulation 0.5h with 10 ℃/min speed, then be warming up to 600 ℃ of insulation 2h with 10 ℃/min speed, further be warming up to 1500 ℃ of insulation 6h with 10 ℃/min speed again, finally be cooled to normal temperature with 5 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 88%, compressive strength is 354MPa, and thermal conductivity and thermal diffusivity are respectively 1.59 ~ 0.77 W/ (mK), (0.77 ~ 0.36) × 10 from room temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.50MPa.
Embodiment 7
1) concentration be respectively to the lanthanum nitrate of 1mol/L and the aqueous solution of basic zirconium chloride and stir 0.5h, forming La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammonia precipitation process agent with the speed of 60ml/min, dropping finishes rear continuation and stirs still aging 20h after 0.5h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, with deionized water wash, separation, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 110 ℃ of temperature, dry 12h, obtains amorphous powder;
2) by amorphous powder ball milling 1h, thermal treatment 6h under 400 ℃ of conditions, ball milling 5h again, screening is processed and is obtained the submicron powder that median size is 900nm, add 4% polyvinyl alcohol solution granulation of submicron powder quality, at 90 ℃ of temperature, dry to polyvinyl alcohol solution content and account for 1% of submicron powder quality, dry-pressing formed under 200MPa pressure, slowly be forced into highest pressure and pressurize 1min makes biscuit, biscuit carried out under 100MPa pressure to isostatic cool pressing and process 0.5min and make zirconic acid lanthanum biscuit of ceramics;
3) zirconic acid lanthanum biscuit of ceramics is warming up to 100 ℃ of insulation 1.5h with 10 ℃/min speed, then be warming up to 400 ℃ of insulation 2h with 10 ℃/min speed, further be warming up to 1550 ℃ of insulation 6h with 10 ℃/min speed again, finally be cooled to normal temperature with 10 ℃/min speed, obtain fine and close zirconic acid lanthanum pottery.
By zirconic acid lanthanum ceramic density and density after Archimedes's drainage calculating sintering; Test the incompressible intensity of zirconic acid lanthanum pottery by universal testing machine; Measure thermal conductivity and the thermal diffusivity of zirconic acid lanthanum pottery by thermal constant analysis tester; By the monolateral pre-CRACKED BEAM subtraction unit test fracture toughness property of fine ceramics.
Pass through correlation detection and calculate, the density of zirconic acid lanthanum pottery prepared by the present embodiment is 86%, compressive strength is 310MPa, and thermal conductivity and thermal diffusivity are respectively 1.55 ~ 0.75 W/ (mK), (0.76 ~ 0.35) × 10 from room temperature to a 1200 ℃ variation tendency
-6m
2/ s, fracture toughness property is 1.47MPa.
The present invention is not limited to the above embodiments; under any, in technical field, have and conventionally know the knowledgeable; without departing from the spirit and scope of the present invention, when doing a little change and retouching, therefore protection scope of the present invention is when depending on applying for a patent being as the criterion that claim scope defines.
Claims (2)
1. lower thermal conductivity, a high strength dense pure phase zirconic acid lanthanum pottery, is characterized in that, the chemical formula of zirconic acid lanthanum pottery is La
2zr
2o
7, be the green stone crystalline phase of single Jiao, density is greater than 85%, and compressive strength is 310 ~ 500MPa, and normal temperature thermal conductivity and thermal diffusivity are respectively 1.55 ~ 1.79W/ (mK), (0.90 ~ 0.76) × 10
-6m
2/ s, 1200 ℃ of thermal conductivities and thermal diffusivity are respectively 0.75 ~ 0.94W/ (mK), (0.35 ~ 0.45) × 10
-6m
2/ s, fracture toughness property is 1.45 ~ 1.70MPa.
2. a preparation method for lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery as claimed in claim 1, is characterized in that its step is as follows:
1) lanthanum nitrate that is 0.1 ~ 1mol/L by concentration and the aqueous solution of basic zirconium chloride also stir 0.5 ~ 1h, form La
3+with Zr
4+mol ratio is the mixed solution of 1:1, mixed solution is added drop-wise in ammoniacal liquor with the speed of 10 ~ 60ml/min, dropping finishes rear continuation and stirs still aging 12 ~ 24h after 0.5 ~ 2h, after leaving standstill, supernatant liquor pH value reaches 10 ~ 13, by deionized water wash, separation for throw out, in the time that supernatant liquor pH value is 7, with washing with alcohol, separation, at 80 ~ 110 ℃, dry 12 ~ 24h, obtains amorphous powder;
2) by amorphous powder ball milling 1 ~ 3h, thermal treatment 3 ~ 6h under 400 ~ 1100 ℃ of conditions, ball milling 3 ~ 8h again, screening obtains the submicron powder that median size is 300 ~ 900nm, add 3 ~ 8% polyvinyl alcohol solution granulation of submicron powder quality, in polyvinyl alcohol solution, the mass percent of polyvinyl alcohol is 5%, at 60 ~ 120 ℃, dry to polyvinyl alcohol solution content and account for 1 ~ 3% of submicron powder quality, slowly be forced into 200 ~ 300MPa pressurize 1 ~ 5min, the dry-pressing formed biscuit that makes, biscuit is carried out under 100 ~ 200MPa pressure to isostatic cool pressing processing 0.5 ~ 3min and make zirconic acid lanthanum biscuit of ceramics,
3) zirconic acid lanthanum biscuit of ceramics is warming up to 80 ~ 120 ℃ of insulation 0.5 ~ 1.5h with 3 ~ 10 ℃/min speed, then be warming up to 400 ~ 600 ℃ of insulation 1 ~ 3h with 3 ~ 10 ℃/min speed, further be warming up to 1400 ~ 1600 ℃ of insulation 4 ~ 10h with 5 ~ 10 ℃/min speed again, finally be cooled to normal temperature with 5 ~ 10 ℃/min speed, obtain lower thermal conductivity, high strength dense pure phase zirconic acid lanthanum pottery.
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| CN111099909A (en) * | 2019-12-30 | 2020-05-05 | 浙江大学 | High-performance ceramic with surface modified polycrystalline mullite fiber compounded with rare earth lanthanum zirconate and preparation method thereof |
| CN111099907A (en) * | 2019-12-30 | 2020-05-05 | 浙江大学 | High-performance ceramic with surface modified zirconia fiber compounded with rare earth lanthanum zirconate and preparation method thereof |
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| CN111099909A (en) * | 2019-12-30 | 2020-05-05 | 浙江大学 | High-performance ceramic with surface modified polycrystalline mullite fiber compounded with rare earth lanthanum zirconate and preparation method thereof |
| CN111099907A (en) * | 2019-12-30 | 2020-05-05 | 浙江大学 | High-performance ceramic with surface modified zirconia fiber compounded with rare earth lanthanum zirconate and preparation method thereof |
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