OXIDATION TEST OF CONCRETES WITH HIGH CONTENT IN SILICON CARBIDE.COMPARISON BETWEEN CONCRETE C AND MCC SIC 80.

Our Technical Department has developed a thorough study of the oxidation. following the same way of researching from some of our previous post (TEIDE REFRACTORY SOLUTIONS, S.L. : HAS CAREFULLY STUDIED THE OXIDATION OF NON SHAPED OF SILICON CARBIDE BASED REFRACTORIES 23TH JANUARY 2013).

Along this research it has been carried out a trial of oxidation of two compositions C and our MCC SIC 80, for long periods of time at a temperature of 1.000ºC.

Following, there are shown the percentages of weight increase after each treatment, related to the Silicon Carbide oxidation, becoming this in oxide of silicon and carbon dioxide, as shown in the reaction:

| | | C | MCC SiC 80 | | -------- | -------- | -------- | | Hours | Fired (ºC) | Oxidation curve | Oxidation curve | | | | % oxidación | % oxidación | | 50 | 1000 |0,75 |0,21 | | 100 | 1000 |2,24 |1,02 | | 200 | 1000 |3,43 |2,02 | | 300 | 1000 |3,79 |2,33 |

Below it is indicated the comparative curves of the weight increase versus the time of the trial.

Analyzing separately each of the materials, it can be easily differentiated that the weight increase as per cent of the C is higher. In this type of qualities weight increase is associated with an increase of the nominal volume of the sample, impacting directly on the geometry of the piece.

The weight increase is also associated with the oxidation of silicon carbide (SiC), thus diminishing its thermal properties as for example the thermal conductivity.

Now is time to analyze the linear variation of bars of 170 mm in length.

Following there are shown the tables with the values of linear variations.

| | | C | MCC SiC 80 | | -------- | -------- | -------- | | hours | Fired (ºC) | % variation |% variation | | 50 | 1000 |0,18 |-0,03 | | 100 | 1000 |0,41 |0,12 | | 200 | 1000 |0,59 |0,32 | | 300 | 1000 |0,76 |0,44 |

Below it is indicated the comparative curves of the linear variation versus the time of the trial..

The physical properties of the two qualities are indicated as follows:

| |MCC SiC 80 | C | | | -------- | -------- | -------- | | Density (110ºC) | 2,58 | 2,41 |g/cm3 | | Porosity (110ºC) | 18 |24 | % | | Porosity (1000ºC) | 24 |29 | % | | Resistance in dry | 252 | 205 | Kg/cm2 | | Resistance 800ºC | 672 | 255 | Kg/cm2 | | Resistance 1200ºC | 817 |803 | Kg/cm2 |

Conclusions:

• The quality MCC SiC 80 is less oxidating than the C quality, achieving an increase in weight and a variation of dimensions less than the studied quality C.