1 Scope of application

This standard applies to test methods for fused and cast synthetic mica used in high temperature insulating materials.

2 Sample pretreatment

After the sample is mechanically processed according to the test requirements, it should be cleaned, and then taken out and placed in a constant temperature drying box.

The temperature is 115±5℃ for 2h, and then cooled to room temperature in a desiccator.

3 test items

31 Bulk density, open (apparent) porosity and water absorption tests

3.1.1 Equipment and Utensils

3111 Electric heating constant temperature drying oven: the temperature can be adjusted to 105～120℃.

3112 Balance: The amount of feeling is 1ml.

3113 Beaker: The capacity is 250ml.

3114 Beaker: The capacity is 2000ml, and a copper mesh is placed 5cm from the bottom of the beaker.

3.1.2 Specimen

Take 5 cylinders with a diameter of about 20mm and a length of about 20mm.

3.1.3 Test Procedure

3.1.3.1 Testing of Drying Quality

Put the sample into a constant temperature drying box, heat it to 115±5℃, dry it for 2 hours, take it out from the constant temperature box, and put it into a desiccator for cooling

After reaching room temperature, weighed with a balance, and the mass accurate to 1 mg was taken as the dry mass M.

3.1.3.2 Saturated Method

The weighed dry mass of the sample is placed on the copper mesh in the beaker. Fill a beaker with distilled water, put it on the electric stove,

Warmed to boiling, boiled for 30 min and cooled to room temperature, the sample was always immersed in distilled water during the whole process.

3.1.3.3 In-water quality test of water-saturated samples

3.1.3.3.1 The saturated sample is placed in a small basket woven with wire with a true diameter of 0.1, suspended on the balance arm, and

Sink to the surface of the beaker filled with distilled water, immerse the small basket and the sample in the distilled water, and weigh, accurate to the mass of 1 mg

for M.

31332 The sample is taken out, and the small basket immersed in distilled water is weighed to the nearest 1mg and the mass is m.

The mass MW of the saturated sample water is calculated according to formula (1):

                                   MW=M-m………………………………………………(1)

In the formula: M——the total mass of the small basket and the sample in water, g;

m - the mass g of the basket in the water.

3.1.3.4 Saturated Specimen Quality Testing

Take the saturated sample out of the water, quickly wipe off the surface water droplets with a saturated towel, and weigh it immediately, accurate to 1 mg.

Mass Mh of the saturated sample.

3.1.4 Computation

Bulk density, open (apparent) porosity and water absorption are calculated according to formulas (2), (3) and (4):

                               M0 ρW

                            ρ=——————…………………………………………(2)

                                Mh-Mw

                               Mh-M0

                            ρ=—————×100……………………………………(3)

                                Mh-Mw

                               Mh-M0

                            ρ=————×100……………………………………(4)

                                  M0

In the formula: ρa——bulk density, g/cm3. Take the arithmetic mean of the sample data, and take the value to two decimal places;

      Pa——Open (apparent) porosity, %. Take the arithmetic mean of the sample data, and take the value with two significant figures.

      W - water absorption, %. Take the arithmetic mean of the sample data, and the numerical aggregate effect number is two digits;

      M0——the mass of the sample after drying, g;

      MW—the mass of the saturated sample in water, g;

      Mh——the mass of the saturated sample in air, g;

      ρw——The density of water at the test temperature, g/cm3.

3.2 Bending strength test

3.2.1 Equipment and Utensils

3211 Universal material testing machine: its indication error does not exceed 1%, the load speed can be controlled, and the load when the sample is broken

It should be within 15-85% of the full scale of the testing machine.

3.2.1.2 Brackets: Specimen and bracket configuration Figure 1. The fillet radius of the indenter is R=5mm, and the distance L between the fulcrums can be adjusted.

3213 Vernier caliper: The division value is 002mm.

3214 External micrometer: the division value is 001mm.

3.2.2 Samples

3221 Sample size: length l=120mm; width b=10±05mm; thickness d=10±02mm.

3222 The load bearing surface and the bottom surface shall be parallel, and the non-parallelism shall not exceed 01mm. The surfaces of the two parallel surfaces shall be smooth and there shall be no obvious machining marks.

3223 Each group of samples shall not be less than 10 pieces.

3.2.3 Test Procedure

3231 Use a micrometer to measure the width and thickness of the central part of the third section of the sample in the longitudinal direction, accurate to 001mm.

3232 Use vernier calipers to adjust the fulcrum spacing L of the bracket to 100±05mm.

3.2.3.3 Put the sample on the support, bear the load at the center, and the average load speed is 2mm/min, and measure the sample.

The load at the break, expressed in Newtons (kg force). The test value when the fracture is outside the central part of three equal parts of the sample is not used.

3.2.4 Computation

The bending strength is calculated according to formula (5):

                                    3L·P

                                  F=—————……………………………… (5)

                                     2b·d2

In the formula: F——flexural strength, MPa (kgf/cm2);

      P——The load when the sample is broken, N (kgf);

      b——the width of the sample, m (cm);

      d——the thickness of the sample, m (cm);

      L——The distance between the fulcrums, m (cm).

Take the arithmetic mean and standard error of the sample calculation data, and take four significant figures for the data.

3.3 Compressive strength test

3.3.1 Equipment and Utensils

3.3.1.1 Universal material testing machine: the indication error is not more than 1%, the load speed can be controlled, and the load when the sample is damaged should be

Within 15-85% of the full scale of the testing machine.

3312 Buffer pad: the buffer pad used between the sample and the contact block, using absorbent paper with a thickness of 04mm.

3313 Micrometer outside diameter: the division value is 001mm.

3.3.2 Samples

3.3.2.1 Specimen size:

Length a=20±062mm; width b=20±02mm; d=25±05mm.

3322 The upper and lower ends of the sample must be parallel and perpendicular to each side, and the height difference of each place shall not be greater than 01mm.

Both end faces are required to be smooth, without obvious traces of machining.

3.3.2.3 There shall be no less than 10 samples in each group.

3.3.3 Test procedure.

3331 Use a micrometer to measure the length and width of the sample, accurate to 001mm.

3.3.3.2 Place the sample in the center of the contact block, and place buffer pads on both ends of the sample.

3333 Continuously increase the load at a speed of 118±24kN/min (1200±2400kgf/min) until the final rupture, and read the total load on the specimen at the time of rupture, expressed in Newtons (kg force).

3.3.4 Computation

The compressive strength is calculated according to formula (6):

                                      P

                                  Rc=——…………………………………………(6)

                                      A

In the formula: Rc——compressive strength of the sample, MPa (kgf/cm2);

      P—the total load on the specimen at the time of rupture, N (kgf);

      A——The area of the sample bearing surface, m2 (cm2).

Take the arithmetic mean and standard error of the sample calculation data, and take three significant figures for the value.

34 Hardness test

3.4.1 Equipment: Standard mineral Mohs hardness, see table below.

                                   Mohs hardness scale

——————————————————————————————————————————

  Hardness grades represent minerals Hardness grades represent minerals

      1 talc 6 orthoclase

      2 Gypsum 7 a—Quartz

      3 Calcite 8 Citrine

      4 Fluorite 9 Corundum

      5 Apatite 10 Corundum

——————————————————————————————————————————

342 Specimen: The surface is smooth and there is no trace of machining.

343 Test method: Mohs hardness is the scratch hardness, and the sample is scratched with standard minerals. For example: Calcite can carve wounds

The sample cannot be scratched by calcite, but the gypsum cannot be scratched by the sample, so the Mohs hardness of the sample is between 2 and 3.

3.5 Average Linear Expansion Coefficient Test

3.5.1 Equipment and Utensils

3.5.1.1 Thermal Dilatometers

35111 Elongation detector: quartz glass push rod type, with differential transformer at the tail, the elongation is less than 1mm, and it can detect

Displacement of 1 μm was measured.

35112 Electric furnace: It can be heated from room temperature to the highest test temperature at a heating rate of 5℃/min.

The zone shall not exceed 2°C over the entire length of the specimen.

3.5.1.1.3 Thermometer: Use a thermocouple to measure the temperature of the sample, and the indicating device has an accuracy of ±5°C.

3512 Micrometer outside diameter: the division value is 001mm.

3.5.2 Specimen

3521 The sample is a cylindrical rod with a diameter of 8 mm and a length of 20 to 25 mm. Both end faces should be perpendicular to the axial direction so that both ends are parallel, not

The parallelism is not more than 004mm, and the end face is flat and smooth.

3.5.2.2 There shall be no less than two samples in each group.

3.5.3 Test Procedure

3531 Measure the length of the prepared sample with a micrometer as L, accurate to 001mm.

3.5.3.2 The sample is placed on the sample holder in the isothermal zone of the electric furnace at room temperature, and placed stably.

3533 The temperature is increased at a heating rate of 5°C/min, from room temperature to 600°C, and the dilatometer automatically records the corresponding elongation of the specimen.

3.5.4 Computation

    The average linear expansion coefficient is calculated according to formula (7):

                                      △L

                                 α1=—————————+A……………………(7)

                                      L(T2-T1)

In the formula: αl——the average linear expansion coefficient of the sample in the process of temperature rising from T1 to T2, K-1 (℃-1);

      △L——The apparent elongation of the sample due to heating, mm;

        L - the length of the sample at room temperature, mm;

      T1——The low temperature in the measurement temperature range. But this temperature should be more than 10 ℃ higher than room temperature;

      A——The calibration value of the test system;

      ΔL——L2-L1, mm;

      L1——the length of the sample when the temperature rises to T1, mm;

      L2——the length of the sample in the temperature rising chamber T2, mm;

Take the arithmetic mean of the calculated data of the sample, and the value is represented by 10-6 after the decimal point.

3.6 Heat transfer coefficient test

The thermal conductivity test adopts the plate steady state method.

3.6.1 Equipment and Utensils

3611 High-temperature heat conduction device: the measuring range is the insulating material with the thermal conduction coefficient below 2kcal/m·h·℃.

3612 Vernier caliper: the division value is 002mm.

3.6.2 Specimen

3.6.2.1 Specimen dimensions. A circular plate with a diameter of 90±1mm and a thickness of 15±2mm.

3622 The surface of the sample shall be ground and polished with abrasive W40, the upper and lower surfaces shall be parallel, and the non-parallelism shall not exceed 0

04mm.

3623 Heat the high temperature part from room temperature to the required temperature, and keep the temperature of the high temperature part in a stable state for 30min.

3.6.2.4 According to the regulations of the instrument, measure the temperature of the high temperature surface, t1, and the total amount of heat transferred by the effective heat transfer area of the sample.

Calorie Q.

3.6.2.5 From room temperature to 600°C