CN114315379A - Glass phase coated zirconia spherical powder and preparation method thereof - Google Patents
Glass phase coated zirconia spherical powder and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of refractory materials, and mainly relates to glass phase-coated zirconia spherical powder and a preparation method thereof. The chemical composition of the zirconia spherical powder coated by the glass phase is w (ZrO)2+HfO2+CaO+Y2O3+MgO+SiO2+Al2O3+Na2O) is more than or equal to 98.0 percent, the zirconia spherical powder is a zirconia spherical powder with an electric melting stable inner core after surface treatment, a coating layer is a glass phase, and the thickness of the glass phase coating layer is more than or equal to 5 mu m and less than 25 mu m; the sphericity of the zirconia spherical powder is 0.7-1; the zirconia spherical powder core electrofusion stabilized zirconia fine powder medium cubic phase C-ZrO2The mass ratio of (B) is 80% or more. The invention improves the compactness of the sintered zirconia refractory product, reduces the sintering temperature, inhibits the phase change of zirconia and prevents the product from cracking during sintering.
Description
Technical Field
The invention belongs to the technical field of refractory materials, and mainly relates to glass phase-coated zirconia spherical powder and a preparation method thereof.
Background
Zirconium oxide (ZrO)2) Is an important inorganic non-metal refractory raw material, has a melting point as high as 2710 ℃, and the zirconia refractory product prepared by using the main raw material has high use temperature, high strength, good wear resistance,The high-temperature resistant ceramic material can stably exist in an oxidizing or reducing atmosphere, and the like, so that the high-temperature resistant ceramic material is widely applied to various high-temperature industrial kilns.
The zirconia has a monoclinic, tetragonal and cubic 3 crystal structure, can generate reversible crystal form transformation along with temperature change and is accompanied with larger volume change; pure zirconia is monoclinic phase in natural environment, when the pure zirconia is heated to 1100-1200 ℃, the pure zirconia is converted into tetragonal phase to generate volume shrinkage, and when the temperature is reduced, the tetragonal phase is converted into monoclinic phase again in the process of 950-1000 ℃ to generate great volume expansion (the volume expansion amount is about 4.7%); this phase change process causes cracking and even pulverization of the pure zirconia article; thus, pure zirconia refractories are almost impossible to produce and use; adding a stabilizer into zirconia, wherein metal ions in the stabilizer enter a zirconia crystal lattice at high temperature, so that a cubic phase or a tetragonal phase (stable phase) can be still maintained at low temperature; common stabilizers are calcium oxide, magnesium oxide, yttrium oxide, cerium oxide, and the like; in addition, hafnium oxide is often associated with the production of industrial zirconia raw materials from minerals. Thus, the zirconia refractory has ZrO as the main chemical component2、HfO2And stabilizers CaO, MgO, Y2O3、CeO2And the like.
The large-size and high-density zirconia bulk ceramic material is a key kiln lining material for special glass melting production. The zirconia block ceramic is usually made by using high-purity zirconia granulated powder as a raw material, and is formed by hydraulic or cold isostatic pressing and then is fired at high temperature. The existing high-purity zirconia granulation powder is prepared by taking zirconia powder prepared by a chemical method or a coprecipitation method and the like as a raw material, adding an organic binder, and then performing spray granulation; the high-purity zirconia granulated powder has high purity (ZrO)2More than or equal to 99.5wt percent of stabilizer), high sintering activity and good fluidity, wherein the stabilizer and the zirconia raw material are distributed relatively uniformly; the high-purity zirconia granulation powder is a high-quality raw material for preparing small-size zirconia compact ceramics; however, in practice, for a single piece of zirconia ceramic with a larger size and a mass of more than 10kg, a green body formed by using the high-purity zirconia granulated powder is seriously cracked after being fired at the temperature of more than 1500 ℃; the main reasons are as follows: (1) the high purity oxidation usedThe zirconium granulated powder has over-high sintering activity and large sintering shrinkage (about 45% of volume shrinkage), which causes cracking of a green body during sintering; (2) the high-purity zirconia ceramics are formed by self-bonding zirconia grains, stress buffering is carried out without a glass phase, and thermal shock resistance is poor, so that a blank body is cracked when the temperature is increased or decreased; (3) the volume effect of phase transformation of tetragonal phase and monoclinic phase in the zirconia ceramic is large in the sintering and cooling temperature range, so that the product is cracked. Therefore, the technical difficulty of preparing the large-size zirconia ceramic product used at the high temperature of more than 1500 ℃ by adopting the high-purity zirconia granulation powder as the raw material is huge.
Practice shows that the zirconia fused cast brick containing about 10 percent of glass phase has higher compactness and excellent thermal shock resistance, so that certain glass phase is introduced into a high-purity zirconia product, so that the glass phase buffers thermal stress in high-temperature use, and the toughness of a large-size zirconia ceramic material is effectively improved. However, the manner of introduction and distribution of the glassy phase are critical for large-sized zirconia compact sintered bodies used at high temperatures: directly mixing the glass phase powder with the high-purity zirconia granulation powder, wherein the glass phase powder and the high-purity zirconia granulation powder are difficult to be fully and uniformly mixed and have poor flowability, so that local glass phase in a blank is enriched and the uniformity of a sintered body is poor; the fully and uniformly granulated powder containing the glass phase causes no aggregate support in the green body and is easy to collapse during firing; the phase composition of zirconia, the microstructure and distribution form of zirconia and glass phase, the chemical composition of the zirconia and the glass phase and the like are key technologies of the zirconia powder raw material containing the glass phase.
Disclosure of Invention
The invention aims to provide zirconia spherical powder coated with a glass phase and a preparation method thereof, wherein the glass phase is uniformly coated on the surface of the electrofusion-stabilized zirconia powder, and the zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity; the large-size zirconia sintered refractory product prepared by taking the zirconia as the main raw material can effectively improve the sintering performance of the product and improve the compactness of the product and the yield of the product during green body processing and sintering.
The invention adopts the following technical scheme for achieving the purpose:
vitreous phase coated zirconia spherical powder, zirconia sphericalThe chemical composition of the powder is w (ZrO)2+HfO2+CaO+Y2O3+MgO+SiO2+Al2O3+Na2O) is not less than 98.0%, wherein w (ZrO)2+HfO2)=70%~85%，w(CaO+Y2O3+MgO)=3%~10%，w(SiO2+Al2O3+Na2O)=8%~25%，w(Na2O) =0.5% -2%; the phase of the zirconia spherical powder is cubic phase C-ZrO2Is a main crystal phase, monoclinic phase M-ZrO2The glass is a secondary crystal phase and contains 10% -30% of a glass phase; the volume density of the zirconia spherical powder is 4.76-5.59 g/cm3(ii) a The granularity of the zirconia spherical powder is more than or equal to 55 mu m and less than or equal to 120 mu m; the zirconia spherical powder is surface-treated, the inner core is electrofusion-stabilized zirconia fine powder, the coating layer is glass-phase zirconia spherical powder, and the thickness of the glass-phase coating layer is more than or equal to 5 microns and less than 25 microns; the sphericity of the zirconia spherical powder is 0.7-1; the zirconia spherical powder core electrofusion stabilized zirconia fine powder medium cubic phase C-ZrO2The mass ratio of (B) is 80% or more.
The invention designs the zirconia spherical powder core coated by the glass phase as the electric melting stable zirconia, and limits the cubic phase C-ZrO of the zirconia spherical powder core2More than or equal to 80 percent, the volume stability of the powder when the powder is used as a refractory raw material is ensured, and when a glass phase between the powder is sintered, the internal electrofused zirconia fine powder still has certain support property; the sphericity of the spherical zirconia powder coated with the glass phase is limited to be 0.7-1, so that the spherical zirconia powder is ensured to have better fluidity, and when the spherical zirconia powder is used as a refractory material, the spherical zirconia powder can be better filled in stacking gaps of other raw materials in a compression molding process, so that the porosity of a product is reduced; by using SiO2、Al2O3、Na2A glass phase component mainly composed of O and the like, and Na contained in the glass phase component2The O component is limited because the glass of the component has higher high-temperature viscosity, and the service temperature of the spherical zirconia powder coated by the glass phase and the product thereof can be increased. The glass phase coated zirconia spherical powder is mainly used as a main raw material of a large-size zirconia compact refractory brick, has good fluidity and certain sintering activityThe porosity of the refractory product after firing can be reduced, and the glass phase introduced by the method can be uniformly distributed in the product, so that the bonding property among the zirconia raw materials is improved, and the mechanical strength of the product is improved. The zirconia product prepared by taking the zirconia spherical powder coated by the glass phase as the raw material has the glass phase distributed among the crystal grains, and the glass phase absorbs the thermal stress at high temperature, thereby improving the thermal shock resistance of the product.
The granularity of the electrofusion-stabilized zirconia fine powder is more than or equal to 45 mu m and less than or equal to 75 mu m, and the main component is ZrO2+HfO2And also contains stabilizers CaO, MgO and Y2O3One or two of, w (ZrO)2+HfO2)≥85%， w(ZrO2+HfO2+CaO+MgO+ Y2O3) More than or equal to 98.0 percent, and cubic phase zirconia is taken as a main crystal phase, wherein the cubic phase C-ZrO2Is greater than or equal to 80 percent.
The mass fraction of CaO in the electrofusion-stabilized zirconia fine powder is less than 0.3% or 4-6%, the mass fraction of MgO is less than 0.3% or 2.5-4%, and Y is2O3The mass fraction is less than 1.0% or 5% -13%.
Removing ZrO from zirconia minerals2The external common accompanying HfO of about 1%2Which has no significant effect on the performance of the refractory, and thus HfO in zirconia refractory2May not be seen as a contaminant; because the pure zirconia has obvious crystal form transformation along with the temperature change and is accompanied with larger volume change, the stabilizing agent is added to form stable solid solution, the cubic phase content is more than or equal to 80 percent, the stability of the zirconia fine powder used as a refractory raw material at high temperature can be ensured, and a certain strength supporting effect can be achieved, so the chemical composition of the electrofusion-stabilized zirconia fine powder is limited.
The raw material of the glass phase can be one or more of clay, glass powder or fused quartz, the purity is more than or equal to 95%, and the granularity is more than or equal to 1 mu m and less than or equal to 8 mu m.
A preparation method of spherical zirconia powder coated by a glass phase comprises the following steps: 1) The method comprises the following steps of (1) taking the electrofusion-stabilized zirconia fine powder as a pelletizing core, and fully mixing the electrofusion-stabilized zirconia fine powder with a binding agent to enable the binding agent to wrap the surface of the zirconia powder; 2) adding a proper amount of glass phase raw materials consisting of one or more of clay, fused quartz and glass powder into the mixture obtained in the step 1) to form zirconia balls coated by the glass phase materials; 3) and drying the pellets and then screening to obtain the glass powder coated zirconia spherical powder.
The preparation method of the glass phase coated zirconia spherical powder can also comprise the following steps: 1) the method comprises the following steps of (1) taking the electrofusion-stabilized zirconia fine powder as a pelletizing core, and fully mixing the electrofusion-stabilized zirconia fine powder with a binding agent to enable the binding agent to wrap the surface of the zirconia powder; 2) adding a proper amount of glass phase raw materials consisting of one or more of clay, fused quartz and glass powder into the mixture obtained in the step 1) to form zirconia balls coated by the glass phase materials; 3) drying the zirconia pellets, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, and screening to obtain glass-phase-coated zirconia spherical powder; in the high-temperature flame spraying treatment process, the glass phase material is softened and filled in surface pores of the electrofusion-stabilized zirconia fine powder, so that the porosity of the raw material is reduced, and simultaneously, the glass phase material is softened and cooled to form a compact glaze-shaped sealing layer on the surface of the zirconia powder.
The preparation method of the glass phase coated zirconia spherical powder is characterized by comprising the following steps: the granularity of the electrofusion-stabilized zirconia fine powder is 45-75 mu m, and the granularity of the glass-phase material is 1-8 mu m.
The preparation method of the glass phase coated zirconia spherical powder is characterized by comprising the following steps: the binding agent is PVA water solution or zirconium sol water solution.
According to the glass-phase-coated zirconia spherical powder provided by the invention, the inner core is zirconia fine powder, the outer shell is a glass-phase coating, the glass-phase-coated zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity, and is used as a raw material for isostatic pressing of large-size and complex-shaped zirconia refractory products, so that the glass-phase-coated zirconia spherical powder is beneficial to improving the density of the sintered zirconia refractory products, reducing the sintering temperature, inhibiting the phase change of zirconia, preventing the products from being sintered and cracked, improving the thermal shock resistance of the products and the like; the powder has simple preparation process, small equipment investment, low energy consumption and easy industrial production.
Detailed Description
The invention is illustrated by the examples given, but is not to be construed as being in any way limited thereto.
Example 1:
weighing w (ZrO)2+HfO2+ MgO) =98% and 75kg of fused magnesia stabilized zirconia fine powder with the particle size of 45-60 mu m, adding 3% PVA aqueous solution, and then fully mixing in a vibration mill for 40min to prepare zirconia fine powder with the surface of the powder uniformly coated with a binding agent; weighing 25kg of clay with the particle size of 3-5 microns, adding the clay into the zirconia fine powder, and continuously and fully mixing to obtain a zirconia pellet coated with a glass phase material; drying the zirconia balls in a 110 ℃ oven for 6h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then screening by using a 180-mesh screen to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of a glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+MgO)=73.5%，w(SiO2+Al2O3=25.5%，w(Na2O) =0.5%, the particle size is 55-80 μm, the thickness of a glass phase coating layer is 5-15 μm, and the average volume density of spherical powder is 4.95g/cm3The sphericity is 0.8 to 1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity, and is a high-quality raw material for preparing large-size compact zirconia refractory products.
Example 2:
weighing w (ZrO)2+HfO2+ CaO) =98%, 85kg of fused calcium oxide stabilized zirconia fine powder with the particle size of 45-55 μm, adding 4% zirconium sol water solution, and fully mixing in a vibration mill for 40min to prepare zirconia fine powder with a binder uniformly coated on the surface of the powder; weighing 15kg of glass powder with the particle size of 5-8 mu m, adding the glass powder into the zirconia fine powder, and continuously and fully mixing to obtain a zirconia pellet coated with a glass phase material; drying the zirconia pellets in a 110 ℃ oven for 6h, and introducingPerforming flame spraying heat treatment to obtain surface vitrified zirconia spherical powder, cooling, and sieving with a 150-mesh sieve to obtain zirconia spherical powder with an inner core of electrofused stable zirconia fine powder and a shell of glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+CaO)=83.7%，w(SiO2+Al2O3)=13.8%，w(Na2O) =2.0%, granularity is 55-105 μm, thickness of glass phase coating layer is 5-25 μm, and average volume density of spherical powder is 5.30g/cm3The sphericity is 0.8 to 1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 3:
weighing w (ZrO)2+HfO2+Y2O3) 90kg of fused yttria-stabilized zirconia fine powder with the grain size of 55-75 mu m and 98.5 percent, fully mixing the fused yttria-stabilized zirconia fine powder with the PVA aqueous solution with the grain size of 5 percent in a vibration mill for 45min to prepare zirconia fine powder with a binding agent uniformly coated on the surface of the powder; weighing 15kg of fused quartz with the particle size of 1-5 mu m, adding the fused quartz into the zirconia fine powder, and continuously and fully mixing to obtain a vitreous phase material coated zirconia pellet; the zirconia balls are dried in a drying oven at 110 ℃ for 6 hours and then screened by a 150-mesh screen to obtain zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+Y2O3)=88.9%，w(SiO2+Al2O3)=10.0%，w(Na2O) =0.5%, the particle size is 60-105 μm, the thickness of a glass phase coating layer is 5-15 μm, and the average volume density of spherical powder is 5.45g/cm3The sphericity is 0.7 to 0.9. The zirconia spherical powder has high sphericity, good fluidity and high sintering activity.
Example 4:
weighing w (ZrO)2+HfO2+ MgO) =98%, 80kg of fused magnesia stabilized zirconia fine powder with the particle size of 45-75 mu m, adding 4% PVA aqueous solution, fully mixing in a vibration mill for 40min, preparing a bonding agent, and uniformly coating the bonding agent on the surface of the powderFine zirconia powder of (4); weighing 10kg of clay with the particle size of 3-5 microns and 10kg of glass powder with the particle size of 5-8 microns, and adding the clay and the glass powder into the zirconia fine powder to continue and fully mix to obtain a zirconia pellet coated with a glass phase material; drying the zirconia balls in a 110 ℃ oven for 6h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then sieving by using a 150-mesh sieve to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of a glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+MgO)=78.5%，w(SiO2+Al2O3+Na2O)=21.5%，w(Na2O) =1.2%, the particle size is 55-100 mu m, the thickness of a glass phase coating layer is 5-20 mu m, and the average volume density of spherical powder is 5.13g/cm3The sphericity is 0.8 to 1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 5:
weighing w (ZrO)2+HfO2+ MgO) =98%, 40kg, w (ZrO) of fused magnesia-stabilized zirconia fine powder with particle size of 60-75 μm2+HfO2+ CaO) =98%, 38kg of fused calcium oxide stabilized zirconia fine powder with the particle size of 60-75 μm, adding 3.5% zirconium sol water solution, and then fully mixing in a vibration mill for 45min to prepare zirconia fine powder with a bonding agent uniformly coated on the surface of the powder; weighing 10kg of clay with the particle size of 3-5 microns and 12kg of fused silica with the particle size of 3-5 microns, and adding the clay and the fused silica into the zirconia fine powder to continue and fully mix to obtain a zirconia pellet coated with a glass phase material; the zirconia balls are dried in a drying oven at 110 ℃ for 6 hours and then screened by a 150-mesh screen to obtain zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+MgO+CaO)=76%，w(SiO2+Al2O3)=23%，w(Na2O) =0.6%, the particle size is 70-105 μm, the thickness of a glass phase coating layer is 5-18 μm, and the average volume density of spherical powder is 5.11g/cm3The sphericity is 0.7 to 0.8. The zirconia spherical powder toolHas high sphericity, good fluidity and moderate sintering activity.
Example 6:
weighing w (ZrO)2+HfO2+ CaO) =98%, and 100kg, w (ZrO) of fused calcium oxide stabilized zirconia fine powder with particle size of 45-55 μm2+HfO2+Y2O3) 60kg of fused yttria-stabilized zirconia fine powder with the grain size of 45-55 mu m and the grain size of 98.5 percent, adding 4 percent PVA (polyvinyl alcohol) aqueous solution, and fully mixing in a vibration mill for 60min to prepare zirconia fine powder with a binding agent uniformly coated on the surface of the powder; weighing 10kg of fused quartz with the granularity of 1-3 mu m and 30kg of glass powder with the granularity of 1-3 mu m, adding the fused quartz and the glass powder into the zirconia fine powder, and continuously and fully mixing the fused quartz and the glass powder to obtain a zirconia pellet coated with a glass phase material; drying the zirconia balls in a 110 ℃ oven for 10h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then sieving by using a 200-mesh sieve to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of a glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+Y2O3+CaO)=78.5%，w(SiO2+Al2O3)=19.5%，w(Na2O) =1.7%, the particle size is 55-70 μm, the thickness of a glass phase coating layer is 5-12 μm, and the average volume density of spherical powder is 5.18g/cm3The sphericity is 0.9-1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 7:
weighing w (ZrO)2+HfO2+ MgO) =98.5% fused magnesia-stabilized zirconia fine powder with particle size of 65-75 μm 110kg, w (ZrO)2+HfO2+Y2O3) 76kg of fused yttria-stabilized zirconia fine powder with the particle size of 60-75 mu m and 98.5%, adding a 5% zirconium sol aqueous solution, and fully mixing in a vibration mill for 60min to prepare zirconia fine powder with a binder uniformly coated on the surface of the powder; weighing 4kg of fused quartz with the particle size of 5-8 mu m and 10kg of glass powder with the particle size of 5-8 mu m, adding the fused quartz and the glass powder into the zirconia fine powder, and continuously and fully mixing the fused quartz and the glass powder to obtain the zirconia balls coated by the glass phase material(ii) a Drying the zirconia balls in a 110 ℃ oven for 10h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then sieving by using a 120-mesh sieve to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+Y2O3+MgO)=90.5%，w(SiO2+Al2O3)=6.7%，w(Na2O) =0.8%, the particle size is 75-120 mu m, the thickness of a glass phase coating layer is 7-25 mu m, and the average volume density of spherical powder is 5.48g/cm3The sphericity is 0.8 to 1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 8:
weighing w (ZrO)2+HfO2+ MgO) =98.5% and 60kg, w (ZrO) of fused magnesia-stabilized zirconia fine powder with particle size of 45-75 μm2+HfO2+Y2O3) 116kg of fused yttria-stabilized zirconia fine powder with the grain size of 45-75 mu m and the grain size of 98.5 percent, adding 5 percent zirconium sol water solution, and fully mixing in a vibration mill for 60min to prepare zirconia fine powder with a bonding agent uniformly coated on the surface of the powder; weighing 12kg of clay with the particle size of 2-5 microns and 12kg of glass powder with the particle size of 2-5 microns, and adding the clay and the glass powder into the zirconia fine powder to continue and fully mix to obtain a zirconia pellet coated with a glass phase material; the zirconia balls are dried in a drying oven at 110 ℃ for 10h and then screened by a 150-mesh screen to obtain zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+Y2O3+MgO)=85.5%，w(SiO2+Al2O3)=14%，w(Na2O) =1%, the particle size is 55-100 mu m, the thickness of a glass phase coating layer is 5-15 mu m, and the average volume density of spherical powder is 4.83/cm3The sphericity is 0.7 to 0.8. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 9:
weighing w (ZrO)2+HfO2+Y2O3) 164kg of fused yttria-stabilized zirconia fine powder with the grain size of 50-65 mu m and the grain size of 98.5 percent, adding 4 percent PVA (polyvinyl alcohol) aqueous solution, and fully mixing in a vibration mill for 60min to prepare zirconia fine powder with a bonding agent uniformly coated on the surface of the powder; weighing 16kg of clay with the granularity of 3-5 microns, 8kg of fused quartz with the granularity of 3-5 microns and 12kg of glass powder with the granularity of 3-5 microns, and adding the clay into the zirconia fine powder to continue and fully mix to obtain a zirconia pellet coated with a glass phase material; drying the zirconia pellets in a 110 ℃ oven for 12h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then sieving by using a 180-mesh sieve to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of a glass phase coating.
The resultant vitreous phase-coated spherical zirconia powder, w (ZrO) thereof2+HfO2+Y2O3)=80%，w(SiO2+Al2O3)=18%，w(Na2O) =1.8%, the granularity is 60-80 μm, the thickness of a glass phase coating layer is 5-10 μm, and the average volume density of spherical powder is 5.17g/cm3The sphericity is 0.9-1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Example 10:
weighing w (ZrO)2+HfO2+ MgO) =98.5% and 150kg of fused magnesia stabilized zirconia fine powder with the particle size of 45-65 μm, adding 3% PVA aqueous solution, and then fully mixing in a vibration mill for 60min to prepare zirconia fine powder with a binder uniformly coated on the surface of the powder; weighing 20kg of clay with the particle size of 1-3 mu m, 20kg of fused quartz with the particle size of 1-3 mu m and 10kg of glass powder with the particle size of 1-3 mu m, and adding the clay, the fused quartz and the glass powder into the zirconia fine powder to continuously and fully mix to obtain a zirconia pellet coated with a glass phase material; drying the zirconia pellets in a 110 ℃ oven for 12h, then carrying out 'flame spraying' heat treatment to obtain surface-vitrified zirconia spherical powder, cooling, and then sieving by using a 200-mesh sieve to obtain the zirconia spherical powder with an inner core of electrofusion-stabilized zirconia fine powder and a shell of a glass phase coating.
The resulting glassy phase coated oxygenZirconium oxide spherical powder of w (ZrO)2+HfO2+MgO)=71%，w(SiO2+Al2O3)=27%，w(Na2O) =1.6%, the particle size is 55-75 mu m, the thickness of a glass phase coating layer is 5-10 mu m, and the average volume density of spherical powder is 4.87g/cm3The sphericity is 0.8 to 1. The zirconia spherical powder has high sphericity, good fluidity and moderate sintering activity.
Claims (6)
1. A spherical zirconia powder coated with a glassy phase, characterized in that: the chemical composition of the zirconia spherical powder is w (ZrO)2+HfO2+CaO+Y2O3+MgO+SiO2+Al2O3+Na2O) is not less than 98.0%, wherein w (ZrO)2+HfO2)=70%~85%，w(CaO+Y2O3+MgO)=3%~10%，w(SiO2+Al2O3+Na2O)=8%~25%，w(Na2O) =0.5% -2%; the phase of the zirconia spherical powder is cubic phase C-ZrO2Is a main crystal phase, monoclinic phase M-ZrO2The glass is a secondary crystal phase and contains 10% -30% of a glass phase; the volume density of the zirconia spherical powder is 4.76-5.59 g/cm3(ii) a The granularity of the zirconia spherical powder is more than or equal to 55 mu m and less than or equal to 120 mu m; the zirconia spherical powder is surface-treated, the inner core is electrofusion-stabilized zirconia fine powder, the coating layer is glass-phase zirconia spherical powder, and the thickness of the glass-phase coating layer is more than or equal to 5 microns and less than 25 microns; the sphericity of the zirconia spherical powder is 0.7-1; the zirconia spherical powder core electrofusion stabilized zirconia fine powder medium cubic phase C-ZrO2The mass ratio of (B) is 80% or more.
2. The vitreous phase-coated spherical zirconia powder according to claim 1, wherein: the fused zirconia fine powder has a particle size of 45 μm or more and 75 μm or less and contains ZrO as a main component2+HfO2And also contains stabilizers CaO, MgO and Y2O3One or two of, w (ZrO)2+HfO2)≥85%， w(ZrO2+HfO2+CaO+MgO+ Y2O3) More than or equal to 98.0 percent, and cubic phase zirconia is taken as a main crystal phase, wherein the cubic phase C-ZrO2Is greater than or equal to 80 percent.
3. The vitreous phase-coated spherical zirconia powder according to claim 1, wherein: the mass fraction of CaO in the electrofusion-stabilized zirconia fine powder is less than 0.3% or 4-6%, the mass fraction of MgO is less than 0.3% or 2.5-4%, and Y is2O3The mass fraction is less than 1.0% or 5% -13%.
4. The vitreous phase-coated spherical zirconia powder according to claim 1, wherein: the raw material of the glass phase can be one or more of clay, glass powder or fused quartz, the purity is more than or equal to 95%, and the granularity is more than or equal to 1 mu m and less than or equal to 8 mu m.
5. A method for preparing the vitreous phase-coated spherical zirconia powder according to any one of claims 1 to 4, characterized by comprising the steps of:
1) the method comprises the following steps of (1) taking the electrofusion-stabilized zirconia fine powder as a pelletizing core, and fully mixing the electrofusion-stabilized zirconia fine powder with a binding agent to enable the binding agent to wrap the surface of the zirconia powder;
2) adding a proper amount of glass phase raw materials consisting of one or more of clay, fused quartz and glass powder into the mixture obtained in the step 1) to form zirconia balls coated by the glass phase materials;
3) drying and screening the zirconia pellets to obtain zirconia spherical powder coated by glass powder; or drying the zirconia pellets, carrying out flame spraying heat treatment to obtain surface-vitrified zirconia spherical powder, and sieving to obtain glass-phase-coated zirconia spherical powder.
6. The method for preparing a vitreous-phase-coated spherical zirconia powder according to claim 5, wherein: the binding agent is PVA water solution or zirconium sol water solution.
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