Particle size analysis of electrical grade magnesium oxide powder;

Particle size analysis of electrical grade magnesium oxide powder;

Due to the different particle sizes of crushed magnesium oxide ore, if a certain amount of ratio is used, it has the following advantages.

1. It can increase the powder density, reduce the working temperature of the resistance wire, and thus improve the lifespan of the electric heating element;

2. Can overcome the "screening" effect; Improve the utilization rate of MgO powder;

Analysis of the state of magnesium oxide powder under heating:

The porosity of MgO powder compressed in a tubular electric heating element is normally 15%, which means that the density of MgO powder is: the true density of MgO powder minus the porosity, which is 3.85 * (1-15%)=3.05 g/cm3. If the temperature of the electric heating element is sufficiently high during operation, the oxygen in the pore reacts with the resistance wire and pipe material. Due to this reaction, the partial oxygen pressure decreases, and the final partial oxygen pressure determines the affinity between oxygen and the metal components of the element. According to data, some oxygen pressures may decrease to 10-13-19ata. At such low oxygen pressure, the properties of the fine particles of fused MgO powder change, which is commonly known as the blackening of MgO powder. Under oxidation conditions, MgO powder mainly evaporates in molecular form at high temperatures without decomposition, and may be partially reduced under reduction conditions. MgO is decomposed as follows:

MgO solid ≈ Mg+1/2 O

According to data, the decomposition pressure of magnesium oxide powder at different temperatures can be calculated using the following equation:

10logP=- (A * 104)/T+BlogT+C * 10-3+D * 10-5 T-2+E

In the formula, P: decomposition pressure (as a value); T: Temperature, 0 K (range 9320K~13930K);

A=2.6061; B=0.2680; C=-0.62578; D=0.0932; E=7.3377.

After substituting the data, it is calculated that:

When T1=9230K (650 ℃), then P1=4.68016 * 10-21

When T2=10730K (800 ℃), then P2=3.92101 * 10-17

When T3=11730K (900 ℃), then P3=4.43868 * 10-15

When T4=12230K (950 ℃), then P4=3.52367 * 10-14

When T5=12730K (1000 ℃), then P5=2.37276 * 10-13

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