From idea to reality: digital engineering principles applied
In 1999, a steel foundry specialising in converter manufacture commissioned NLV Solar AG to develop a high-temperature material. There had been no advances in this area in 30 years: furnaces were still clad with traditional refractory ceramics, which have problematic characteristics, or with aluminium titanate, which is expensive to produce.
Target specifications for the new material:
- heat resistance to at least 1700–2000°C
- an expansion coefficient of zero
- resistance to high pressures
- non-toxic
- simple processing
- capable of injection into negative forms for casting moulds
- manufacturing process suitable for scaling-up to mass production.
Development process
First, the specifications were formulated as a mathematical problem with unknown factors. An ideal material with the corresponding properties was digitally modelled and tested against various chemical formulae extracted from databases. When an exact match was found, a digital prototype was designed and tested through iteration in virtual models. Numerical interpretation is the key, coupled with experience in evaluating the results. The next step was to build and test the first physical prototype.
Development took six months: from idea to digital prototype in three months; DP to final physical prototype in three months. The material, over 90% quartz sand in composition, was ready for pilot testing in industrial conditions. A converter was lined with the material and 200 tons of molten iron were poured through. When the test rig was dismantled, the material emerged from the slack unblemished and came through the heat shock test – i.e. being thrown glowing into cold water – with flying colours. Nullanium was born. This innovative refractory material can be applied by spraying onto the substrate. In terms of heat resistance, at 3600ºC it far exceeds the melting point of iron, which was the target specification.