Ceramic and Advanced Material tests

Learn what additional tests can be performed on ceramic and advanced material samples to better understand their physical properties.

Bricks, tiles, porcelain, pottery, glass, cement and concrete are all universally useful materials that have different purposes that we have discovered over the centuries. Whilst tiles have been placed on walls, floors and roofs (inside and out) we have been employing glass in windows and smartphone screens. More recently, advanced ceramics have been engineered for highly specific applications; silicon nitrides and tungsten carbides designed for making exceptionally hard, high-performance cutting tools, silicon dioxide and alumina used in making microchips and lithium-silicon oxide is used to make the heat-protective nose cones of space rockets.

These high-tech ceramic materials can be simple compounds or composite materials depending upon the desired end-product properties and their ordinary/extraordinary purposes. Whether they are visibly employed in the aerospace or construction industry for extraordinary applications or basic building materials or cutting tools, they can also be found hiding inside electrical and electronic material where they are chosen for different property reasons. Amongst the varying properties of scratch-resistance, heat-resistance, durability, hardness, strength, insulation or superconductivity in advanced industrial ceramics, there is also the need for ceramics in the world of medicine. The piezoelectric transducers that create ultrasonic waves used in pregnancy scans, hard dentures made from porcelain or bone implants that are cleverly designed to be porous so they promote natural bone growth – all incredible new uses for a well-known field of materials. And then, of course, there is the whole new world of 3D printing!

Whilst the development of new ceramic materials is helping to meet the growing demand in industrial and laboratory applications there is, and always will be, the need to measure and quantify the properties of both the raw materials and finished products in order to verify that their mechanical integrity is as required and expected. This is where a Texture Analyser/Materials Tester can be employed to compress, bend, stretch, extrude, cut, puncture or snap a product and provide an objective analysis of the material’s physical capabilities.

Here are just a few examples of typical ceramic product measurements and, where possible, a publication of where the instruments have been found in action.

Properties that can be measured:

Strength of Green Compacts

To produce structural parts from ceramics using a sintering process from powdered form, the powders must first be pressed into compacts at room temperature before baking in a furnace. The green compact resulting from this is not useful until it is sintered, but it must have sufficient strength to allow manipulation such as machining, and handling before sintering. This can be affected by many factors such as compacting pressure, powder properties, geometry and apparent powder density.

The strength of the compact can be measured using a compressive test, having accurately measured its dimensions, or using a Brinell hardness measurement in a flat sample surface. This book features the use of the Stable Micro Systems for these purposes.

Properties of Powders used in Green Compacts and 3D Printing

When a ceramic powder is used in powder manufacture of solid parts, the occurrence of caking or clumping can cause defects. Additionally, when the powder is being handled on an industrial level, a sample prone to caking can cause ratholes and expensive delays in the factory. The tendency of a powder to form clumps can be measured quantitatively using a number of measurements on a Texture Analyser. Static measurements include Unconfined Yield Stress, and Powder Vertical Shear Strength, whereas the Powder Flow Analyser , presents a widely-used dynamic measurement.

The bulk density of the powder can influence green compact strength. This can also be measured using the Powder Flow Analyser which uses a conditioning sequence to ensure powders have identical preparation before measurement, and a split vessel to cut the powder volume into a consistent volume. This measurement can be automatically combined with the measurement of powder caking, cohesion or speed flow dependency.

The manufacturer must know how a powder will respond to applied stress, including its relaxation behaviour. This can be measured using the Indexable Powder Compaction Rig, or for a more detailed analysis, the High Tolerance Powder Compaction Rig. For automated relaxation tests, the ALIS (Automated Linear Indexing System) can be used. These powder properties are equally applicable to powders used in 3D printed parts, an industry which is expanding rapidly in the ceramics field.

See a typical example in the powder metallurgy industry here.

Strength of Ceramic-Metal, Ceramic-Resin or Ceramic-Ceramic Bonds

The measurement of bond strength is of large interest to the dental industry, where strength of joins in the mouth, such as veneers and implants, are important to the application of these components. These bonds are generally tested in shear, although some publications have recommended a tensile or flexure test. All are possible using a Texture Analyser.

See a typical example in the dentistry industry here.

Strength of Joint Replacements

When a ceramic joint prosthesis is manufactured for use in the body, it is important to have full knowledge of its physical and chemical properties. These involve strength and fatigue testing of the whole component, or specific parts of the component under a set loading configuration. A range of strength and fatigue tests are possible using the TA.HDplus Texture Analyser, with a loading range of 0.5-750kgf.

See a typical example in the medical industry here.

Cyclical Fatigue of Ceramics

A property often associated with metal structures, cyclical fatigue can be a problem with ceramic materials too. When a high-performance ceramic is used as a structural component (such as at high temperatures in engines), knowledge of the effect of cyclic loading on fatigue failure is crucial, due to fluctuating stresses and strains. This is also an important effect on ceramics used in less extreme environments, such as ceramic crowns in the mouth or as stacked capacitors, as they undergo cyclic loading as a matter of course. Cyclical fatigue may be measured in compression, tension or flexure.

See a typical example in the dental industry here.

See a typical example in the electronics industry here.

General Compressive Testing

See a typical example in the dental industry here.

See a typical example in the bioceramics industry here.

See another typical example in the bioceramics industry here.

See a typical example in the medical industry (diametral compression) here.

See a typical example in the electronics industry here.

Patent – see how Ibidem Co. Ltd. used their Texture Analyser to measure breaking strength of the honeycomb structure filter fired body here.

General Tensile or Adhesive Peel Testing

See a typical example in the electronics industry here.

See another typical example in the electronics industry here.