High purity submicron and micron size silicon nitr

Because the silicon nitride powder can resistance to elevated temperatures, use as the remover can make the silicon material easier to mould unloading, and prevent the molten silicon adhesive with the crucible and separate them to make sure the purity of the silicon material. As our silicon powder is according to the needs of customers, the grain size control should operate under the condition of guarantee the thick and uniformity of the coating and guarantee the process of the spraying the spray gun is smooth. So far most of the enterprises use the standard is 250g silicon nitride add to 1000ml ionized water (with 270kg ingot) to spray. If in the actual operation process, the concentration of too much or too thin, you can add some ionized water or increase the powder. When making cast-multicrystalline silicon in the process of melting material and growth of crystal, the molten silicon has overlong contact with the crucible will lead to viscosity. As two products have different thermal expansion coefficients if silicon material and sidewall of crucible combine tightly, it will cause the crystal silicon or crucible broken when the crystal is cooling. In addiction, the molten silicon has overlong contact with the crucible will erode the ceramic crucible and make the multicrystal silicon' s oxygen concentration higher. In order to solve these problems, in craft generally use SN material as the coating of the inside well of the crucible so that it can separate the molten silicon from the crucible. In that case, the viscosity problem is solved and lowers the concentration of the impurity such as the oxygen and carbon of multicrystal silicon. In most cases, use the directional solidifying technology to make cast-multicrystalline silicon, the crucible is the consumable and can not reuse. That means every time may cost one ceramic crucible. If use the SN coating, the ceramic crucible can reuse and greatly reduce the production cost.