Elkem refractories- advanced solutions and support

Elkem Refractories offers high quality microsilica, silicon powders and complementary products for the production of advanced refractory and ceramic products globally. Our products are backed by a highly competent staff for customer service, technical assistance and product development.

Materials for refractories

High quality microsilica, silicon powders and specialty products for advanced refractories and ceramics. Highly competent staff for customer service, technical assistance and product development.

Elkem produces a wide range of silicon qualities for the ceramic industry and we continuously work to developed a product range with both beneficial particle size distributions and chemistry for our ceramic customers.

How to...

  • Improve flowability
  • Dense castables
  • Improve strength during heat-up
  • Make mullite matrix
  • Improve hot strength

How to improve the flow properties of castables

Even small amounts of microsilica will improve the flow properties of a castable. The dense particle packing achieved by microsilica additions will minimise the amount of water needed for casting. This gives low porosity and high strength properties in the fired product.

See a video on the benefits of the microsilica on the flow properties.

For more information you can read our research papers here:

Technical papers: Particle Packing.

How to develop dense castables with low porosity

Due to their small particle size, microsilica particles fill the voids between larger aggregates and give dense castables. A denser castable has lower permeability, higher strength and higher thermal conductivity.

The reactivity of microsilica particles combined with their fine distribution allows for a more efficient cement reaction, i.e. optimising the effects of a low cement content.

For more information you can read our research papers:

Technical papers: Particle Packing.

How to improve strength at intermediate temperatures during heat-up

When mixing microsilica with water, some of the surface molecules dissociate and enable a coagulation of microsilica particles. A network of coagulated particles form a thickening gel which gives improved green strength for castables with very low cement contents. Additionally, the gel structure assures strength during heat-up by counteracting the strength degradation caused by dehydration of cement at temperatures between 200-800°C.

In cement-free basic castables, the gel formation includes silica, magnesia and water.

For more information you can read our research papers here:



How to understand mullite formation and design mullite matrix

Mullite bond-phase is beneficial for high temperature properties in alumina-silicate systems.

In castables the mineralogical make-up of the bond-phase goes through several intermediates during heat-up before

ending up with the desired physical and mineralogical properties at service temperature.

If the composition of the bond phase is incorrect, the result may lead to softening and refractory failure at a much lower temperature than anticipated.

A key to proper design is adequate microsilica content.

You can find more information here:
Research papers:  Let us Make a Mullite Matrix.
Technical papers: Mullite Formation.

How to improve strength at high temperatures

The submicron, amorphous microsilica particles are highly reactive during sintering which results in improved ceramic bonding at reduced firing temperatures.

In alumina based castables, microsilica reacts with alumina to form mullite. This crystalline phase has high refractoriness, and gives a castable high mechanical strength at service temperatures up to 1800°C.

In basic refractory castables, microsilica reacts with magnesite to form forsterite - another refractory ceramic bonding.

For more information you can read our research papers here:

Technical papers: Mullite Formation.

Specialities

The SioxX® product range is tailor-made for use in microsilica-containing unshaped refractories.

Si-NINE silicon powders

Metallurgical silicon is selected, crushed and milled to silicon powders.  Different purities and sizes are offered according to customer requirements and application needs.