ENHANCED PROTECTION Zirconia-enhanced alumina offers superior mechanical strength, abrasion resistance and fracture toughness in wear linings protecting components such as inlet heads
Following the successful introduction of its locally manufactured zirconia- enhanced alumina ceramic products for wear protection applications in South Africa, industrial lining and materials handling solutions provider Groupline Projects is exploring options to expand the availability of the products throughout Africa and in Australia.
In January, Groupline Projects – a subsidiary company of Wonderstone, fully owned by mining and investment group Assore – introduced the GLZ TUFF and the GLZ SUPA TUFF product ranges. The ranges offer an alternative solution to the standard 92% alumina wear ceramics that have historically been the benchmark in ceramic wear applications in the mining and power generation industries. GLZ TUFF offers a cost- effective 3.8 g/cc zirconia-enhanced alumina, while GLZ SUPA TUFF offers a more specialised 4.1 g/cc option.
Wonderstone director and GM Barnard van Loggernberg explains that, while alumina ceramics are very hard and very resistant to low-angle-impact abrasive wear, they have proven brittle during the high-angle impact experienced in components such as cyclones, feeders, vibrating screens, pump impellers and fan blades. Micro-cracks, thus, commonly form in the wear linings under these conditions and grow with repeated impact, ultimately leading to equipment failure.
The addition of zirconia to the alumina, however, creates ceramics with a crystal structure that has undergone a transformation toughening process. During this process, under applied stress, finely dispersed zirconia crystals change from a tetragonal arrangement to a monoclinic arrangement, causing a 3% to 5% volume expansion that absorbs the applied stress.
“With its high mechanical strength, superior abrasion resistance and fracture toughness, zirconia-enhanced alumina is an ideal wear protection solution for demanding applications in South Africa.”
In the past, zirconia-enhanced products were traditionally used only in a limited number of high-wear applications – such as pump components, valve seals and bushes – owing to the high cost of the material. However, with GLZ-TUFF, Groupline Projects can offer the wear technology at a more affordable price, making its use in larger installations, such as pipes, chutes and mill linings, feasible. The products are available as standard tiles or can be engineered to fit irregular shapes.
“Groupline Projects has done extensive testing in mill linings, as well as field tests at a local iron-ore mine that have proven that the new formulation lasts four to five times longer than standard 92% alumina tiles. We have already seen a positive response to GLZ TUFF, with the improved wear life of the product ensuring better equipment availability and decreased plant maintenance costs.”
In addition, van Loggernberg points out that a longer lining wear life means less production downtime and lower maintenance costs for the operator, enabling the zirconia- enhanced alumina to provide a lower total cost of ownership than other materials in high-wear applications.
He further highlights that the zirconia- enhanced products reduce the weight placed on structures, as thinner tiles can be installed that effectively perform as well as tiles twice their thickness and weight.
Forty years ago, wear ceramics was relatively unknown in the mining and power generation industries, but Groupline Projects can now offer the market advanced wear technology improvement that is likely to play a major role locally and internationally, he adds.
“The full impact of this technology will become clear only after more wear time, but we are excited about the prospects surrounding this locally produced product,” Van Loggernberg concludes.