Properties and uses of ceramics

Ceramic materials are abundant on earth. Their varied chemical composition is very important because it includes a significant part of the 118 items of the periodic table. Oxides, alumina and zirconia are made of oxygen elements and a transition metal. Silicates are oxides of mixed origin naturally containing silica. in addition to oxides are non-oxides, such as carbides (e.g. silicon carbide), nitrides, silicides, tellurides, etc. the intrinsic properties of all its phases provide the properties for various uses.

img_7004The specific properties of ceramic parts are largely dependent on the properties of the raw materials used to design them.

Therefore, complete knowledge of the materials is essential in terms of responsiveness, stability, chemical purity, particle size distribution, etc.

From the choice of materials to the creation of the finished product, through recycling, synthesis, characterisation or processing, we can help you with your “materials” problems through dedicated equipment.

Our synthesis and formulation laboratory enables the development of high-performance materials suitable for every industrial use. The processes are implemented from powders or precursors in order to achieve the expected characteristics.

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Synthesis and formulation laboratory equipment

Comparative table of the main classes of technical ceramics

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The important applications of technical ceramics are listed below

BIOCERAMICS ARE USED IN MEDICAL SYSTEMS (BIOREACTORS, SURGICAL INSTRUMENTS AND MEDICAL TOOLS), IN THE FIELD OF RECONSTRUCTIVE SURGERY (PROSTHESES, BONE SUBSTITUTES, EYE IMPLANTS), AND IN DENTISTRY (DENTAL IMPLANTS, BRIDGES, BRACKETS).

Bioceramics are destined for insertion in a living organism.

Alumina is most commonly used in orthopaedics and aluminosilicates are mainly used in dental prostheses.

Zirconia has also been proposed for osteo-articular prosthesis heads. Calcium phosphates are the closest synthetic materials to the mineral phase of bone. They are bioactive and promote growth of bone in contact with them (osteoconduction).

Their composition is varied to control their degradation rate in the body: the most calcium-rich phase (HAP) is bioinert while β-TCP, richer in phosphate, is bioresorbable. These materials are widely used in orthopaedic surgery and maxillofacial surgery.

The CTTC accompanies you in your product development and meets your needs for manufacturing or bioceramics analysis:

CERAMIC COMPONENTS ARE RECOGNISED IN THE FIELD OF TELECOMMUNICATIONS THANKS TO PROPERTIES ALLOWING SYSTEMS TO RESIST THE THEIR ENVIRONMENT AND STRESS TO WHICH THEY ARE SUBJECTED (HUMIDITY VIBRATIONS, TEMPERATURE CHANGES, ETC.).

Compact and powerful, the developed ceramic micro-systems are used in  applications such as interconnect modules for optical fibres (zirconia), photonic band gap antennas, frequency filters, resonators, etc.

In collaboration with laboratories and research institutes in Limoges (SPCTS and XLim), the CTTC is exploring new technologies for shaping ceramics to reduce the size of components without compromising performance.

CERAMICS PRESENT A GREAT DIVERSITY OF ELECTRICAL PROPERTIES FROM SUPERCONDUCTORS TO THE BEST ELECTRIC INSULATION.

Ceramics for electronic use are the most varied in their composition and use. They include electrical insulators (Al2O3, MgO, SiO2, Si3N4, AlN, etc.), semiconductors (SiC, Cu2O, ZnO, TiO2, etc.), electrical conductors (ReO3, MoSi2, LaB6, Ti3SiC2, etc.), ionic conductors (YSZ) or magnetic ceramics with ferrite (Fe3O4, NiFe2O4, etc.).

These ceramics represent 75% of the worldwide turnover for technical ceramics and their applications are numerous: substrate, capacitor, varistor, sensor, heating elements, solid electrolyte, piezoelectric or superconductor, etc.

For each of these applications, the selection and implementation of these ceramic materials determine the final properties of the components.

Also, the CTTC can assist you in establishing your specifications, improving your product or developing a specific solution:

WHETHER STRUCTURAL OR FUNCTIONAL, CERAMICS HAVE NUMEROUS APPLICATIONS IN THE AERONAUTICS AND SPACE SECTOR: TURBINE BLADES, TELESCOPE MIRRORS, SENSORS, COMBUSTION CHAMBERS, HEAT SHIELDS, PLASMA ENGINES, ETC.

Focus on structural ceramics

Structural ceramics must resist high mechanical stresses. Carbides (SiC, B4C, etc.) and nitrides (Si3N4, BN, etc.) are commonly used in the aerospace, automotive and mechanical industries: ball bearings, seals, cutting tools, turbines, telescope mirrors, etc.

To overcome the natural brittleness of ceramics, the ceramicist had to develop specific architectures on the micro or macro scale.  Ceramic matrix composites or CMC, which contain silicon carbide fibres or carbon, have excellent mechanical properties that are resistant under extreme temperature conditions. Lamellar architecture or particulate reinforcement composites, such as ZTA (Zirconia Toughened Alumina), have considerably improved resistance to the propagation of cracks. New materials, such as MAX phases (e.g. Ti3SiC2), have original mechanical behaviour (high temperature plasticity, dissipating the energy of crack propagation).

The CTTC develops technology solutions tailored to your specifications and allows you to develop manufacturing processes or create prototypes through:

TECHNICAL CERAMICS HOLD A PARTICULARLY IMPORTANT PLACE IN THE FIELD OF ENERGY AND THE ENVIRONMENT.

Ceramics are commonly used as filters or membranes when the surrounding environment is very aggressive (high temperature, corrosive fluid, etc.).

Ceramic foams are used, for example, for filtration of aluminium alloys of smelters. They can eliminate inclusions and reduce trapped gas. Silicon carbide filters are designed to filter impurities from steel, grey cast iron and bronze.

Particulate filters are composed of an extruded ceramic honeycomb structure and the channels are clogged alternately to force the passage of gas through the porous walls. Silicon carbide is used because it has high thermal conductivity, which can dissipate heat from soot combustion, and high thermal shock resistance.

Catalytic converters also have ceramic honeycomb structures in which a catalyst is deposited on the surface to degrade gaseous emission pollutants. The catalytic converter is usually made from a low expansion coefficient oxide (cordierite) while catalysts are oxide powders (Al2O3, CeO2, CeO2 / ZrO2 and zeolite) on which noble metals are deposited (platinum, rhodium and palladium).

Ceramic membranes with controlled porosity can be used to filter particles in liquid effluents. Dense ceramic membranes are used at a high temperature to separate the gaseous species by selective permeation. The latter category includes materials such as zirconia rendered ion-conductive by doped yttrium used as a solid electrolyte in fuel cells (SOFC) or lambda sensors, and perovskite oxides, which are both ionic and electronic conductors used in catalytic membrane reactors.

Another important area of use is in the nuclear sector where ceramics are used as fuel (UO2, PuO2), refractory materials, storage elements or for rendering waste inert.

Severe stress (high temperatures, extremely corrosive environments) to which ceramics are subjected require the use of efficient and specific materials for each application.

The CTTC has the expertise and equipment required to develop and create the ceramics alongside your teams to meet your needs, from the design phase to the scale 1 prototype: