Electrical insulation and high-temperature electrical insulation specialists Insulectric and Interhom have partnered with the Department of Science and Technology’s Technology Localisation Implementation Unit (TLIU) to develop asbestos-free cement-board insulators. This partnership was established in 2012 as the company was included in the Firm Technology Assistance Package of the TLIU.

Once the products – IG31, IG32 and IG33 – have been developed, Interhom will be the only manufacturer in South Africa that will ensure the import replacement of several different foreign- sourced products, says TLIU manager Ashley Bhugwandin, adding that current demand for asbestos-free cement board is high in the international market and, therefore, susceptible to international competition.

He tells Engineering News that the asbestos-free cement boards have been under development at the Council for Scientific and Industrial Research (CSIR) for two years and that the science council hopes that the products will be launched onto the South African market in 12 months, at competitive prices.

“When CSIR Built Environment was approached, the unit had already developed fibre composite technologies that could be applied successfully in developing these boards. The products were developed using high-aspect- ratio reinforcements, with different tests undertaken to confirm that the reinforcements could replace asbestos in terms of keeping the properties of the board in check regarding dielectric strength, thermomechanical properties and functionality,” Bhugwandin explains.

He adds that cement-board insulators are used in electrical appliances, such as switchgears, to insulate certain areas, owing to the amount of current that runs in an apparatus.

“We initially had to look broadly at options that considered reinforcement characteristics, costs, availability and quality issues. We therefore had to do some initial characterisation to ensure that we were considering alternative products that could potentially replace asbestos,” explains CSIR Built Environment materials research group leader Dr Joe Mapiravana.

The asbestos-free cement boards are produced as flat boards, which are then cut into customised shapes using computer numerically controlled machines to create components for particular applications.

Mapiravana notes that Insulectric – an original-equipment manufacturer that produces complete integrated devices or units – has several customers that will define the design and manufacturing of the boards, as well as the sizes into which they will be cut. Customers include those using high-voltage switchgears in electrified railway wagons, power producers and distributors, and base and precious metals smelters and refiners that use electric arc and induction furnaces.

During normal use, these components experience wear and degradation, ultimately requiring refurbishment. Should components fail, the complete unit will be returned to Insulectric to be refurbished.

The boards will have a variety of applications, including energy generation, energy distribution and energy use. The products are currently in the commercialisation stage and the CSIR has worked closely with clients to determine customer needs and demands.

Bhugwandin adds that the product applications all depend on customer specifications, which allows for customisation. “This is a massive import substitution, and what has attributed to the success of this project is the essential involvement of the industry players throughout all stages of the project to the extent that they even made their facilities available for testing. It is almost a joint venture project within the industry.”

Initial testing of the asbestos-free cement boards presented excellent dielectric strengths, which provided 50% more capability. The characterisation of the products considered mineralogy and microstructure, using scanning electron microscopy, X-ray diffraction and differential thermal analysis; and mechanical properties, such as elastic modulus, flexural strength, fracture toughness, thermal-shock resistance, thermal-expansion behaviour and electrical properties, high-voltage dielectric strength and surface breakdown voltage. These aspects were used to guide developers in the creation of the products and to set certain standards.

“The CSIR is very well equipped for such advanced research work. For most of the development work, excluding high-voltage testing at the South African Bureau of Standards, in Pretoria, we relied on the available research infrastructure,” says Mapiravana.

The asbestos-free cement boards are environment friendly, safer in terms of their potential hazard to health and they promote job creation at Interhom and in the downstream industry, owing to the demand for local materials. They also increase South Africa’s competitiveness and export potential, says Bhugwandin.