Ceramics

Ceramics are composed of compounds of metals and non metals and may be crystalline or partly crystalline. They are characterized as brittle, hard, strong in compression, and weak in shearing, tension and impact. These materials are also very resistant to both corrosion and very high temperatures and can be designed to either insulate against or selected to conduct electricity. Ceramics have a wide range of applications most notably in industries that require materials to withstand large compressive forces or intense heat exposure for extended periods of time.

Ceramics Testing:

Testing ceramics helps determine if they are suited for specific applications. Typically this involves a series of tests to measure the material’s mechanical properties. These properties include the yield strength, ultimate strength, tensile strength, compressive strength, flexural strength, fracture strength, hardness, fracture resistance and creep rate. With the knowledge of these values the behavior that is expected from the ceramic during the application can be predicted and it can be shown if it will succeed or fail.

Common Ceramics Test Methods:

There are many different tests that can be performed upon ceramics but the most common and important are those that involve compression, tension, flexural, and fracture mechanics. Because of the way that ceramics are constructed they generally posses vary high compressive strengths and will most often fail due to tensile, flexural or fracture forces; therefore it is very important to test these properties. Each property may also be tested using conventional methods, creep mechanics or cyclic (fatigue) methods.

Material Testing Specimens:

Depending on the method of testing a ceramic test sample can come in several different forms. For compression testing a ceramic sample is usually in the sample of a simple brick, cube or cylinder. Flexural and fracture testing require the sample to be smaller than compression testing but it is still rectangular in nature with the flexure sample generally as a thin rectangle and the sample for fracture ranging from a beam to a brick. A ceramic sample for tensile testing presents interesting obstacles as they are very brittle in nature and prone to fracturing when loaded improperly. The sample is generally the same as other tensile samples with the exception of the ends which are usually formed as button headed to fit into specially designed grips to avoid any incidental failure.

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Applicable Standards

• ASTM C1161 Flexural Bend Ceramics Test Equipment
• ASTM C1211 Flexural Testing for Ceramics
• ASTM C1273 Tensile Ceramic Test Equipment
• ASTM C133 Crush Modulus Rupture Refractories Test Equipment
• ASTM C1399 Residual Strength Fiber-Reinforced Concrete Test Equipment
• ASTM C1421 Fracture Toughness Ceramics Test Machine
• ASTM C1424 Compression Ceramics Test Machine
• ASTM C1499 Equibiaxial Flexural Ceramics Test Equipment
• ASTM C1550 Flexural Toughness Testing of Fiber Reinforced Concrete
• ASTM C1557 Tensile Fibers Test Equipment
• ASTM C158 Flexural Bend Testing for Glass
• ASTM C1674 Ceramic Flexural Strength Test Equipment
• ISO 14125 Plastic Composites Flexure Bend Test Machine
• ISO 14126 Compression Fiber-Reinforced Plastic Composites Test Machine
• ISO 14130 Flexure Short Beam Plastic Composites Test Equipment
• ISO 22214 Fine Ceramics Cyclic Bending Fatigue Testing