CERAMICS: A WORLD OF ITS OWN WITH FASCINATING POSSIBILITIES
Steel is the native language of the designer, they say. So while they are on safe ground for metals – and increasingly for polymers as well – this is rarely the case for ceramics. Many development projects therefore have emergency situations. A conversation with a ceramic specialist who could help many a constructor.
- Development partner for high performance sintered ceramics
- Low density, high temperature resistance and hardness
- Medical technology is an important field of application for sintered ceramic components
“We are often the point of contact for design departments from all sorts of industries who are no longer aware of problems with conventional materials in their development projects,” reports Harrie Sneijers, Sales Director at Formatec Ceramics in the Dutch town of Goirle. This is due to the fact that sintered ceramics have completely different property spectra and undergo a completely different manufacturing process than metals. Many designers who are used to metals or plastics encounter a new, completely unfamiliar world. This begins with the fact that ceramic does not plastically deform, but can suddenly break brittle under incorrectly selected conditions of use. Also, many designers are unfamiliar with the fact that dimensional changes of 20 to 30 percent have to be taken into account during the manufacturing process and that larger wall thicknesses or wall thickness changes can adversely affect the products. This lack of experience often leads to setbacks in the development process.
ENGINEERING PARTNER FOR ALL TYPES OF CERAMICS
“The consequences can be dramatic if time and cost budgets are exceeded and projects get into difficulties,” reports Sneijers from practice. With such cases, he and his colleagues are so busy that they almost feel reminded of a hospital emergency room. They are well equipped to solve a wide variety of tasks.
Formatsc has a full range of sintered ceramic component manufacturing techniques, including ceramic injection molding (CIM), 3D printing and mechanical processing of pellets, using a range of materials such as zirconia (ZrO 2 ), Alumina (Al 2 O 3 ) and silicon nitride. In addition, there are materials with special properties such as ESD (no static charge) or the mixed oxide ATZ (Al 2 O 3 + ZrO 2), which is characterized by particularly high flexural strength with simultaneous biocompatibility, so that it is used, for example, for dental implants. Formatec works closely with customers to develop new solutions.
ADVANTAGES OF SINTERED CERAMIC COMPONENTS
“Compared with metals or plastics, ceramics are characterized by low density, high temperature resistance and hardness”, Sneijers names three major material advantages. Added to this are corrosion and wear resistance, low coefficients of thermal expansion, mostly good thermal and electrical insulation and insensitivity to most solvents and chemicals. The temperature resistance of silicon nitride (Si 3 N 4 + additives) is 1,200 ° C, Al 2 O 3 ceramics and ATZ withstand even 1,600 °. They maintain their good mechanical strength up to temperatures at which most metals already deform under their own weight.
Also impressive are the increases in flexural strength: While in 1950 this was just 150 MPa for aluminum oxide porcelain, today ATZ materials reach 2,000 MPa. Another advantage of practically all ceramic materials is their very high hardness of about 1,350 HV for ZrO 2 up to 2,000 HV for Al 2 O 3 . Additives can be used to set special properties on a case-by-case basis, such as antistatic behavior, electrical conductivity or colorful colors. Although Formatec prefers to work with commercially available standard compositions, it also develops special materials, if required, right up to exotic materials, for example for nuclear medicine applications.
VARIOUS APPLICATIONS IN MEDICAL TECHNOLOGY
” Medical technology is a very important field of application for sintered ceramic components”, Sneijers calls a field of application. The reason for this is above all their excellent biocompatibility. This is why medical experts often prefer sintered ceramics to metals, including implants that are intended to remain permanently in the body. Examples include joint prostheses such as acetabulum or knee joints. The use of ceramic instead of metal reduces the risk of unwanted reactions.
Another interesting application is dental implants. So far, dental implants from ATZ were often milled from pressed blanks. CIM injection molding enables cost reductions of up to 75 percent. In addition, thanks to the possibilities of the injection molding process, the outer contour of the inserts is given a special fine structure which promotes rapid and safe bone ingrowth.