Do you know the Operating Process of Fused Silica?
Apr. 07, 2021
As a Silicon Domes Manufacturer, share with you.
(1) This operation process is suitable for silica sol, the surface layer or transition layer of the shell.
(2) The silica sol used in this process is the same as the zircon powder coating, which is 30% silica.
(3) The wetting agent and defoaming agent in this process operation are the same as the zircon powder coating.
(4) The flow cup viscometer used in this operation is Zahn 5# cup, and the outlet aperture is Φ5.28mm.
(5) Coating preparation:
Fused Silica Windows
1. The preparation of fused silica powder, 320 mesh (network number: 0.044) 275 mesh (network number: 0.052) 200 mesh (network number: 0.076) 120 mesh (network number: 0.125) The mass fraction of SiO2 in the fused silica powder is 99.5% or more. Among them: 320 mesh accounts for 50%, 200 mesh accounts for 25%, and 120 mesh accounts for 25%. The percentage is calculated as mass fraction, that is, weight ratio.
2. The viscosity of the paint is 50~60 seconds, strictly controlled not to be less than 50 seconds, 60 seconds is the best viscosity. It can obtain the best surface finish castings; when used in the production of carbon steel or 430 series, the viscosity can be reduced to 40 seconds.
(6) Hanging sand:
1. Use fused silica sand with 80-100 mesh (50-100 mesh) 50%, and corundum sand with 80 mesh, 50%.
2. Use fused silica sand 80-100 mesh (50-100 mesh) 100%, (50-100 mesh)
3. Use corundum sand 80 mesh 100%.
The above three kinds of hanging sand can be used, but the casting is operated on the production site according to the difference and combined with the surface quality. (7) Matters needing attention:
1. Strictly control the proportion of paint preparation, no randomness, and strict on-site operation tracking. The viscosity measurement of the flow cup must be accurate, and the viscosity must be measured each time before making the surface layer.
2. When a two-layer layer is needed, the second time is the transition layer, the paint viscosity is 28~36 seconds.
3. The surface shelling technology is a serious and meticulous operation technology. It is necessary to ensure that the coating thickness is uniform, otherwise it will produce permeable or pitted castings. The gravity of the sand hanging is relatively uniform, and it is comprehensive.
4. The thickness of the surface layer under different viscosities in the case of fused silica wet film is: the viscosity in 50 seconds is 0.2mm, the viscosity in 40 seconds is 0.18mm, the viscosity in 30 seconds is 0.15mm, and the viscosity in 20 seconds is 0.12mm.
5. Fused silica sand: 50~100 mesh is 0.325~0.15 of the national standard mesh number, and the mesh size is 0.3~0.15mm of ASTME11-70.
6. The hanging sand of the second layer can be the same as the operation of the original zircon powder surface layer process, or 30~50 mesh (screen size 0.6~0.3mm) fused silica sand can be used.
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