You're looking for ceramic materials that can withstand high temperatures. How do you find the best ones?

1 What are ceramic materials?

Ceramic materials are inorganic, non-metallic solids that are usually composed of metal and non-metal elements, such as oxides, nitrides, carbides, and borides. They have a crystalline or semi-crystalline structure, which gives them high hardness, strength, and wear resistance. Ceramics also have low thermal and electrical conductivity, high melting points, and good chemical stability. These characteristics make them ideal for applications that involve high temperatures, corrosive environments, and mechanical stresses.

2 What are the main challenges for high-temperature ceramics?

Ceramic materials have advantages, but they can also face limitations and challenges when exposed to high temperatures for prolonged periods. For example, thermal expansion mismatch can cause thermal stresses and cracks, especially if the ceramics are bonded or coated with other materials. Additionally, ceramics are prone to fracture due to sudden changes in temperature, such as rapid heating or cooling, or thermal cycling. This is because ceramics have low toughness and ductility, meaning they cannot absorb or dissipate the energy from the thermal shock. Furthermore, ceramics can deform or sag over time when subjected to high temperatures and constant loads - a phenomenon known as creep. Creep depends on temperature, stress, time, and material composition.

3 How to define the requirements for high-temperature ceramics?

Before you start searching for ceramic materials that can withstand high temperatures, it is important to define the specific requirements and constraints for your application. You need to consider the operating temperature range, thermal expansion coefficient, thermal shock resistance, creep resistance, and any other properties that are relevant for the application. Additionally, you must determine the minimum and maximum temperatures that the ceramic material will encounter, as well as the frequency and duration of the temperature cycles. Furthermore, you should assess how much the ceramic material will expand or contract when heated or cooled and how compatible it is with other materials in the system. Additionally, you must determine how resistant the ceramic material is to sudden changes in temperature, how much it will deform or sag over time when exposed to high temperatures and loads, and how critical the dimensional accuracy and mechanical integrity are for your application. Other properties include density, porosity, hardness, strength, modulus, fracture toughness, fatigue resistance, wear resistance, corrosion resistance, electrical conductivity, thermal conductivity, optical properties etc.

4 How to search for high-temperature ceramics?

Once you have defined the requirements and constraints for your application, you can begin to search for ceramic materials that can meet or exceed them. To do this, you can consult scientific papers, books, reports, and patents that describe the properties and performance of ceramic materials under high-temperature conditions. Additionally, there are online and offline databases that contain information on the properties and characteristics of ceramic materials. Moreover, you can use software tools to select the best ceramic materials for your application, based on your requirements and constraints. These tools rank and screen ceramic materials according to their performance indices derived from the properties and objectives of the application. In short, there are various methods and tools available to help you find and compare high-temperature ceramics.

5 How to evaluate and test high-temperature ceramics?

After narrowing down your list of potential ceramic materials, you need to evaluate and test them to verify their suitability and reliability for your application. There are various methods and techniques that you can use to measure and analyze the properties and behavior of ceramic materials under high-temperature conditions. For example, thermal analysis methods, such as differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA), can be used to determine the thermal properties and transitions. Meanwhile, mechanical testing methods, like tensile, compression, bending, shear, fatigue, creep and fracture toughness tests can be utilized to analyze the mechanical properties and strength. Additionally, microstructural characterization methods such as optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) or X-ray diffraction (XRD) can be employed to examine the microstructure and composition of ceramic materials.