Recovering bubbles in the firing process of ceramic cups
1. Features
The base foam that occurs due to insufficient recovery is the recovery bubble. The diameter is larger than the oxidation bubble, also known as the extreme bubble, and the cross-section is yellow, which mostly occurs in the finished product near the fire mouth at high temperature.
2. The reason
The main reason is that the recovery of sulfate and high-valent iron in the green body is not enough, and foaming occurs at high temperature.
①The temperature of the oxidation furnace is too high. When the oxidation is finished, the temperature in the kiln is too high.
② Strong recovery air is not enough.
③The power outage lasts for a long time, so that the product cannot be recovered in time.
④The firing temperature is too high.
3. Prevention essentials
① Properly reduce the temperature of the oxidation furnace, so that the temperature in the strong recovery stage is appropriate.
②The recovery air and firing temperature should be properly controlled.
glaze bubble
1. Features
The glaze bubbles are generally fine, bulging on the surface of the glaze layer, easy to touch with hands, and stick to black dots after breaking.
2. The reason
The main reason is that the deposited carbon or dissociation is not burned out before the glaze is melted, and after the glaze is melted, the gas generated by the burning of carbon is not easy to escape, but is wrapped on the surface of the glaze layer.
① The temperature of the oxidation furnace is improper, and the temperature difference in the kiln is too large at the end of the oxidation, so that the oxidation of the green body is insufficient, or the recovery is premature.
② In the stage of strong recovery, the air is too strong, resulting in carbon deposition.
③ The initial melting temperature of the glaze is low or the temperature rises too fast, and the glaze vitrifies prematurely.
④The content of high-temperature pollutants (carbonate, sulfate) in the glaze is high.
3. Prevention essentials
① Control the temperature of the oxidation furnace properly to reduce the difference between the high and low temperature of the preheating zone.
② Strong recovery air is appropriate.
③ Increase the initial melting temperature of the glaze, or reduce the content of high-temperature decomposed substances in the glaze.
Post time: Feb-13-2023