**Introduction to GB/T 4741-1999: Method for Testing Bending Strength of Ceramic Materials**
This standard outlines the procedure for determining the room temperature bending strength of ceramic materials using a three-point loading method. It specifies the testing equipment, sample preparation, test procedures, result calculations, and data processing. The method is applicable to ceramic materials and related auxiliary materials.
**Standard Test Method for Bending Strength of Ceramic Materials**
Published by the National Bureau of Quality and Technical Supervision, proposed by the National Light Industry Bureau.
The standard defines the necessary equipment, sample requirements, and testing steps. It also includes detailed instructions on how to calculate and process the results.
**2. Definitions**
Bending strength limit refers to the maximum stress that a specimen can withstand before breaking under static bending force. It is calculated as the ratio of the bending force to the section modulus at the point of fracture.
**3. Equipment**
- **Bending strength testing machine**: Must have an error margin of no more than 1%, with a constant-speed loading system. The loading and support blades should have a diameter of 10 mm ± 0.1 mm.
- **Vernier caliper**: Accuracy of 0.2 mm.
- **Oven**: Capable of maintaining a temperature of 110°C ± 5°C.
- **Dryer** and **balance**: Sensitivity of 0.1 g.
**4. Sample Preparation**
- Rectangular samples measuring 10 cm in length, with a width-to-thickness ratio of 1:1.
- Samples must be produced under the same conditions as in actual manufacturing.
- They should be processed neatly without visible defects.
**5. Test Procedure**
- Dry the samples in the oven at 110°C ± 5°C until they reach a constant weight, then cool them in a desiccator.
- Place the sample on the support blades, ensuring the distance between the supports allows 10 mm of the sample to extend beyond each blade.
- Apply load at an average rate of 10–50 N/s until the sample breaks. Record the maximum load.
- Measure the width and thickness of the fractured surface with a vernier caliper, accurate to 0.1 mm.
**6. Data Processing**
- If the maximum relative deviation exceeds 10%, discard the sample with the largest deviation and recalculate.
- If more than 4% of samples are discarded, the test must be repeated.
- Use the arithmetic mean of the valid samples as the final bending strength value, rounded to 0.1 MPa.
**7. Test Report**
Include details such as the sample delivery unit, name, number, span, loading speed, dimensions, data discarding, and test results. Also, note the date, personnel, and testing organization.
**Determination of Water Absorption Rate, Apparent Porosity, and Bulk Density**
**1. Scope**
This standard provides methods for determining water absorption, apparent porosity, apparent density, and bulk density of ceramic tiles. Two methods are used: boiling and vacuum saturation. Boiling is suitable for classification, while vacuum is used for more precise measurements.
**2. Principle**
Dry ceramic tiles are suspended in water after being saturated. This helps calculate the relationship between dry mass, saturated mass, and submerged mass.
**3. Instruments**
- Oven (110 ± 5)°C.
- Boiling heater, heat source, balance (0.01% accuracy), deionized water, desiccator, and weighing containers.
- Vacuum tank capable of achieving 100 ± 1 kPa for 30 minutes.
**4. Specimens**
- 10 whole bricks per type.
- For larger bricks, adjust the number based on surface area or mass.
- Cut large pieces if needed, but ensure all fragments are included in the measurement.
**5. Test Steps**
- Dry the samples in the oven until constant weight is achieved.
- Saturate the samples using either boiling or vacuum methods.
- Weigh the samples in a dry state and after water absorption.
- Calculate water absorption, porosity, and bulk density based on the measured masses.
**Implementation Date:** Approved on November 1, 1999, effective from January 1, 2000.
This comprehensive standard ensures consistent and accurate evaluation of ceramic materials, supporting quality control and product development across industries.
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