Alumina bubble insulation brick is a new type of lightweight thermal insulation material. Since its application, it has quickly occupied the high-temperature kiln market with its excellent properties such as light weight, high temperature resistance, and good thermal insulation and energy saving effect. At present, Alumina bubble insulation brick mostly use alumina bubble balls as aggregate, alumina powder or micropowder as matrix material, phosphoric acid or aluminum dihydrogen phosphate as binder, and are fired at high temperature. The main component is single, Al2O3 The content is as high as 98%. Therefore, the thermal shock stability is not good, and it becomes one of the key factors affecting its service life during use, especially in the environment with large temperature differences; and a single component composition easily leads to structural defects of the product, such as the abnormal growth of alumina crystals results in low mechanical strength of the product. Therefore, it is objectively necessary to find alumina bubble bricks with better thermal shock resistance and higher strength to overcome the defects of traditional bubble bricks.
In order to solve the problems of poor thermal shock stability and low strength of alumina bubble brick in the prior art, which result in short service life, the present invention provides a zirconium-containing alumina bubble heat insulation brick and a manufacturing method thereof. Zirconia has excellent mechanical properties and fracture toughness. Its melting point is 2715℃, which is much higher than 2050℃ of alumina. It is widely used in toughened alumina ceramics. On the other hand, zirconia has low thermal conductivity. The thermal conductivity of this ion-doped zirconia ceramic is only 1～2W ·m-1 ·K-1, which is much smaller than the 10W ·m-1 .K-1 of corundum, and zirconia is more resistant to acid and alkali corrosion than alumina strong ability.
The present invention adopts the following technical solutions
It includes the following ingredients:
Alumina bubble ball 40～69%
Alumina powder 21～46%
Zirconium powder 5～14%
Binding agent 8.5～12%;
The sum of the above composition percentages is 100%.
Introduction of raw materials:
The alumina bubble balls are one or a combination of alumina bubble balls with an aluminum content of ≥99.2% or alumina bubble balls with a zirconium content of 5%.
Alumina powder is an aluminum powder prepared by a calcination process.
The zirconium-containing powder material is one or a combination of monoclinic zirconia, yttrium oxide or magnesium oxide, stabilized zirconia, zircon, zirconium corundum, and zircon mullite.
The binding agent is one or a combination of aluminum sulfate, aluminum dihydrogen phosphate, phosphoric acid, and dextrin.
The particle size of the above-mentioned component particles is: alumina bubble ball 0～3mm, fine alumina powder 3～5um, monoclinic zirconia 3～5um, yttria or magnesium oxide stabilized zirconia 3～5um, zircon 325 mesh, containing zirconium oxide (Zircon/Zircon corundum/Zircon mullite) 325 mesh.
.jpg)
The approximate production steps of zirconium-containing alumina bubble ball insulation brick are as follows:
(1) Weigh alumina micropowder and zirconium-containing powder respectively, put the weighed alumina micropowder and zirconium-containing powder in a vibrating mill and mix for 15-20 minutes, and set aside;
(2) Mix the weighed alumina bubble balls and the binder evenly, then add the mixed alumina powder and zirconium-containing powder mixture in step (1), stir evenly and vibrate on a vibrating table to form a semi-finished product;
(3) Dry the molded semi-finished product at a temperature of 110-130°C for 12-48 hours, then fire it at a temperature of 1550-1680°C for 8-10 hours, and then naturally cool it to room temperature to make a finished product.
According to the above technical solution, the advantageous effects produced by this invention are as follows:
(1) Zirconia is added to the alumina bubble brick, and the dispersed ZrO2 grains are used to produce martensitic transformation, forming a certain number of micro-cracks in the matrix. These cracks nucleate and expand under the action of the crack tip stress. Plays the role of consuming and dispersing the energy of the main crack tip, hindering the expansion of the main crack; at the same time, the existence of microcracks reduces the Young's modulus of the material, thereby reducing the elastic strain stored in the material that causes thermal shock fracture of the material Therefore, it contributes to the improvement of the thermal shock stability of the material.
(2) The elastic modulus E of ZrO2 is higher than that of corundum. The addition of this kind of high elastic modulus second phase particles prevents the transverse cross-section shrinkage when the matrix material is stretched, and to achieve the same transverse shrinkage as the matrix, it must be increased tensile stress, so that the material consumes more energy, thereby playing a role in toughening. At the same time, the particles with high elastic modulus play a "pinning" effect on the cracks, deflect the cracks and detour, and also play a toughening role.
(3) ZrO2 is added as the second phase, as a second phase inclusion on the corundum grain boundary to pin the movement of the grain boundary, which can effectively prevent the abnormal growth of corundum particles, and the refined matrix structure can improve the material strength.
Detailed ways
The present invention can be explained in more detail through the following embodiments. The purpose of disclosing the present invention is to protect all changes and improvements within the scope of the present invention. The present invention is not limited to the following embodiments.
Example 1
A kind of zirconium-containing Alumina bubble insulation brick , its composition includes oxide with a particle size of 0～3mm and an aluminum content of ≥99.5%
69% of aluminum alumina bubble balls, 21% of 3~5um alumina fine powder, and 10% of 325 mesh zircon fine powder.
The sum of the weight percentages of the above components is 100%, and the following additional weight percentages are added. The calculation basis for the addition amount is the sum of the weights of the above components. Aluminum sulfate and aluminum dihydrogen phosphate composite binder 8.5%.
The specific preparation method of the zirconium-containing alumina bubble heat-insulating brick is as follows:
(1) Weigh the alumina powder and zircon powder according to the above requirements, mix the weighed alumina powder and zircon powder for 15-20 minutes, then place the weighed in a vibrating mill and mix evenly before use ；
(2) Mix the weighed alumina bubble balls and the binder uniformly and add the mixed alumina micropowder and zircon powder mixture in step (1), and then vibrate and form a semi-finished product on a vibrating table after mixing uniformly;
(3) The molded semi-finished product is dried at 110°C for 12 hours, then fired at 1550°C for 8 hours, and then naturally cooled to room temperature to make a finished product.
Example 2
Ingredients include 35% alumina bubble balls with a particle size of 0～3mm and aluminum content ≥99.5%, 25% of alumina bubble balls with a particle size of 0～3mm and zirconium content of 5%, and 35% of alumina powder with 3～5um. , 3 ~ 5um monoclinic zirconia or oxide stabilized zirconia (yttria or magnesium oxide stabilized) 5%.
The sum of the weight percentages of the above components is 100%, and the following additional weight percentages are added. The calculation basis for the addition amount is the sum of the weights of the above components. Dextrin 12%.
The specific manufacturing method of the zirconium-containing alumina bubble ball insulation brick is as follows: except that the semi-finished product is dried at 130°C for 48 hours, the firing temperature is 1680°C, and the heat preservation is 9 hours, the rest is the same as in Example 1.
Example 3
The ingredients include 50% alumina bubble balls with a particle size of 0-3mm, 36% alumina fine powder with a particle size of 3-5um, and 14% zirconium mullite fine powder with 325 mesh.
The sum of the weight percentages of the above components is 100%, and the following additional weight percentages are added. The calculation basis for the addition amount is the sum of the weights of the above components. Phosphoric acid 10%.
The specific manufacturing method of the zirconium-containing alumina alumina bubble ball insulation brick is as follows: except that the semi-finished product is dried at 110°C for 12 hours, the firing temperature is 1580°C, and the heat preservation is 8 hours, the rest is the same as in Example 2.
Example 4
Ingredients include 20% alumina bubble balls with a particle size of 0-3mm and aluminum content ≥99.5%, 20% alumina bubble balls with a particle size of 0-3mm and 5% zirconium content, and 46% alumina powder with a particle size of 0-3mm and 5% zirconium. , 3 to 5um monoclinic zirconia 3%, 325 mesh zirconium corundum fine powder 11%.
The sum of the weight percentages of the above components is 100%, and the following additional weight percentages are added. The calculation basis for the addition amount is the sum of the weights of the above components. Phosphoric acid 10%.
The specific manufacturing method of the zirconium-containing alumina alumina bubble ball insulation brick is as follows: except that the semi-finished product is dried at 130℃ for 24 hours, the firing temperature is 1620°C, and the heat preservation is 10 hours, the rest is the same as in Example 1.
.jpg)
