Sandvik Materials Technology (SMT) reports that Powder Metallurgy materials under its Kanthal brand have been used to boost the productivity of industrial heat treatment furnaces. Efficient heat treatment is a vital step in the production of a wide range of products, from integrated circuits for smartphones to solar cells and most steel- and aluminium-based products. For efficient heat treatment to be possible, industrial ovens have to cope with the extreme heat required for these processes, often up to 1,250°C.
“A common problem is that the construction components within heating systems deform over the course of time,” explained Bo Jönsson, technical specialist at Kanthal. “For a material to function properly at high temperatures, two essential properties are required: good form stability and oxidation resistance.”
“The types of material traditionally used in the construction of industrial furnaces are often nickel-based, which provides good form stability but limited oxidation-resistance.” However, conventionally produced materials – based on iron, chromium and aluminium – have excellent oxidation properties but relatively low form stability.
In May 2017, SMT received the ‘Wilhelm Haglund Medal to the Product Developer of the Year’ award for the development of two materials able to cope with extreme temperatures, which it called Kanthal APM™ and Kanthal APMT™. “The Kanthal APM and Kanthal APMT materials combine uniquely high oxidation resistance and form stability,” Jönsson continued. “The key to successfully developing these properties was the use of Powder Metallurgy to obtain an optimum microstructure in the materials.”
The Powder Metallurgy technique made it possible for the company to structure the metal with billions of small particles, substantially boosting its strength at high temperatures. The materials are now used in applications such as heating systems for industrial furnaces and other demanding uses.
“One example is furnace rollers for continuous annealing lines made from Kanthal APMT, that eliminates the need for water cooling,” Jönsson added. “This provides significant energy savings and environmental benefits. In many cases it has also been possible to reduce maintenance needs and boost productivity as a result of increased process temperatures and fewer shutdowns.”
Jönsson stated that he sees significant opportunities for expanding the use of Powder Metallurgy materials. For example, the development of Kanthal APMT has contributed to Sandvik’s new involvement in a number of projects relating to a fossil-free energy supply.
“The combustion of bio-based fuels generates corrosive environments that our materials have demonstrated good abilities to resist,” he explained. “They could even be of use in the next generation of nuclear power plants. And for large-scale concentrated solar power to be cost-effective, new materials are needed that can handle and store solar energy at higher temperatures.