Stage

Main Response

Changes and Phenomenon

Stage Termination Characteristics

The first stage

Removes the adsorbed water in the porcelain powder, and the temperature of the powder body rises from room temperature to 150 °C

The adsorbed water in the porcelain powder evaporates and escapes in a large amount, and some electrolytes begin to decompose.

The second stage

The organic matter is oxidized, the structural water begins to be removed, the surface of the iron billet is also oxidized, and the temperature of the powder billet rises from 150 °C to 400 °C.

The gas generated by the reaction is removed, tiny cracks appear in the powder layer, and the oxygen in the small hole (gas channel) firing chamber passes through the gas channel and directly reacts chemically with the surface of the iron billet to form iron oxide.

Some fine ceramic powder particles begin to sinter.

The third stage

The powder layer is sintered and a reduction reaction begins. The temperature of the powder body was raised from 400°C to 600°C.

Continue to exclude structural water, the powder layer is completely sintered. Due to the local softening of the porcelain powder, the gas channel begins to be closed, and the oxidation rate of the iron sheet decreases.

The redox reaction between the adhesion agent and the iron billet begins, but the adhesion has not yet formed. Gas removal is very difficult.

The fourth stage

Forms a smooth porcelain surface and produces adhesion. The temperature of the powder blank rises from 600 ℃ to the firing temperature, generally 880~920 ℃, and the low temperature enamel is about 760 ℃.

The porcelain powder is all melted, and erodes the surface of the iron billet, dissolving iron oxide, and the densifying agent is replaced by iron and deposited on the surface of the iron billet. The iron blank and the ground coat penetrate each other, producing a dense layer in the form of dendrites.

The porcelain surface is smooth, there are still small holes, and the adhesion is starting to form.

The fifth stage

Break through and bridge the cells and achieve good adhesion. This is the key stage of sintering, and the sintering temperature is 880~920℃.

The fluidity of the ground coat melt is good, the redox reaction between the adhesive and the iron billet is vigorously carried out, and the gas is easily removed, and the formed holes will be bridged by the molten ground coat. Keep the firing time for a certain time, so that the adhesive and the porcelain surface can reach a good level.

Porcelain surface is smooth and close to ideal. If it is still out of the oven, it will produce an over-burning defect.

The sixth stage

Cooling

After the product leaves the kiln, the temperature gradually decreases, and the residual stress varies with the cooling speed.