A ceramic connection

Materials World magazine
,
1 Aug 2008

International company Morgan Technical Ceramics acquired Certech and Carpenter Advanced Ceramics from Carpenter Technology Corporation in a US$145m deal earlier this year, creating one of the largest technical ceramics companies in the world. Rupal Mehta caught up with the UK team to gain an insight into the business drivers and materials challenges and trends that underpin MTC’s activities.

Back in 2003, we were on a break-even year,’ says Morgan Technical Ceramics’ (MTC) Marketing Director Keith Parker. That was when two former subsidiaries of The Morgan Crucible Company plc – Morgan Advanced Ceramics and Morgan Electro Ceramics – were combined to form MTC. The team introduced a number of tools as part of an 'aggresive growth strategy'.

'The first thing was to look after our existing customers,’ explains Parker. ‘So we began a detailed analysis of what they buy from us and why.’

The executive team also put together a more coherent approach for mentoring business development projects, as well as identifying and nurturing the company’s ‘distinctive competencies’, be it in relation to specific material properties, production capabilities or customer service.

Mergers and acquisitions have since become part of the strategy. Parker says, ‘We were looking for companies that would make a difference to our business.’ Morgan Crucible Company acquired Certech and Carpenter Advanced Ceramics from Carpenter Technology Corporation, based in Wyomissing, USA, in March this year in a US$145m deal. This has expanded MTC’s workforce to 3,000 and added nine manufacturing sites, bringing the total to 24. They are located in Mexico, Australia, the USA, Germany, China and the UK.

Moving on with materials

A manufacturer of components for major markets that include medical, aerospace, automotive, semiconductor processing, and security and defence, MTC is confident about its future in spite of heightened competition and energy costs. ‘At the moment there is talk about a global recession – but we are aligning ourselves to good growth markets,’ insists Parker.

One area of development is the manufacture of ceramic cores for air cooling passages in aircraft and industrial gas turbine (IGT) blades. This is particularly pertinent as these sectors strive to run engines faster and more efficiently at higher temperatures. The material used to make these cores at the site in Corby, UK, (formally part of Certech) is new to the MTC fold.

The cores are made from a mixture of ceramic materials, which include silica and zircon with varying silica contents of 74-96%. These parts have complex geometries to enable air to flow in a certain direction around the centre of the blade, turbulating the air and cooling the component from the inside. During manufacture the ceramic mould is destroyed, leaving an imprint of these air-cooling paths within the component.

The cores themselves are made using proprietary wax pressure ceramic injection moulding. This enables cores for over 400 types of blade to be produced, with complex shapes, varying dimensions and delicate features such as thicker and thinner sections within the same part and cross-hatch square holes. These would be ‘extremely expensive’ to manufacture via conventional computer numerical control mill machining or isostatic pressing techniques as the ceramic is ‘extremely abrasive’, explains Stephen Hogan, General Manager at Corby.

‘The matrix of the material allows us to low pressure inject [it] into these forms without a great amount of wear. This could be applied to other products,’ he adds.

The team at MTC now hopes to develop the technology further by applying a rapid prototyping process, from its existing Stourport site in the UK, for quicker routes to market. The steel tool/mould used in the injection moulding can cost up to £200,000 to manufacture, and this is ‘often on a whim of a design’ for a core from customers, says Parker. The client then verifies the efficiency of the core, often resulting in amendments to the design, which requires another tool and so on. ‘That’s a costly decision’, notes Parker.

A customer has therefore agreed to test cheaper prototype latex or aluminium tools made from CAD models. If applied, the technique will allow the customer to make incremental adjustments to the design before investing in the final tooling for manufacture.

Purity power

The acquisition has also added two other new materials to MTC’s range – a 99.8% purity alumina and magnesia partially stabilised zirconia. With material purity paramount for medical instruments and semiconductor processing, MTC sees strong potential for the new alumina.

Parker says, ‘We had a range of aluminas from 80-99.5%, but we did not have a high purity alumina that we could use for large components. Hip joints are small parts and we press them at high pressures, but if you start to produce large components [from these aluminas] they generally crack during firing. We had been trying [therefore] to develop a high purity alumina, but in the meantime our competition – Carpenter’s site in Auburn, USA – was significantly ahead.’

The two grades of magnesia partially stabilised zirconia at Carpenter’s former site in Melbourne, Australia, are meanwhile used where wear and corrosion is a problem, such as for tooling to make metal cans, or for valves, pumps and oil wells. Parker adds, ‘We did have this material but the materials at Melbourne offer greater mechanical strength and toughness. We have not fully exploited wear and mechanical shock resistance applications because we did not have the complete range of materials’.

On the horizon

The roadmapping of future technological trends is also vital, supported by collaborative R&D. One programme with Sheffield University, UK, looks at injection moulding a biocompatible grade of titanium. Morgan Technical Ceramics uses titanium bonded with a ceramic for medical implant devices such as pacemakers. The titanium is usually machined from solid blocks of cast metal.

‘One of the problems with titanium is that it is an extremely expensive material and difficult to form into shapes,’ explains Mike Thomas, Technical Director at MTC. ‘The advantage of injection moulding is that you form complex geometries without expensive machining, but nobody has been able to maintain the chemical composition to injection mould biocompatible grades.’ The project is in its third year and still at laboratory scale.

The technical team is also starting a new project on lead-free piezoelectric devices in light of the EU Restriction of Hazardous Substances Directive. At the moment, ‘there is nothing that comes close to even 50% of the properties of lead-based peizoelectric materials’, says Thomas. The company is looking for relevant research partners.

Powering ahead

Over the past year, some areas of R&D have come to fruition. Recently, MTC adapted its 99% semiconductor-grade alumina for use in a new sector – the solar panel industry. Original equipment manufacturer Oerlikon Solar, based in Trubbach, Switzerland, is using ceramic bars from MTC to lift and stack glass panels in its thin-film deposition photovoltaic machine. The company says the stainless steel bars used have ‘a tendency to buckle and bend in very high temperatures. We use ceramic bars at 200ºC because of their thermal and chemical stability’.

‘The main challenge is to produce a consistent flatness and parallelism over the 1.4m length of the bar, [whereas for] a semiconductor, you are talking about a diameter of 300mm,’ explains Commercial Manager at MTC’s site in Rugby, UK, Yannick Galais. ‘So we had to modify our equipment in-house to expand the traverse length.

’Energy is a field that Galais intends to keep a closer eye on as the demand for advanced materials grows to meet strict environmental and energy efficiency criteria.

Medical matters

The company has also, this year, brought to market an alumina matrix composite (AMC). Designed to combine the flexural toughness of zirconia and wear resistance of alumina, the material provides improved properties for components such as hip joints.

The AMC has fracture toughness values that are 12% greater, and wear rates 25% lower, than the alumina equivalent. Its flexural strength values are also 38% greater, allowing thinner sections to be produced for abcetabular cups in hip joints to accommodate larger femoral heads.

‘The rationale for bigger femoral heads is less chance of dislocation and they are similar to normal femoral head sizes,’ explains Roy Mason, General Manager at the Rugby plant. ‘Typically, the [implant] heads have been 28-32mm, but the actual femoral head is larger, and heads of up to 60mm are being considered. This is available in metal but ceramic is catching up.’

Thomas adds, ‘People have been working on AMCs or equivalents for a long time, but it’s new for the biomedical market, which is conservative. At the moment, there is a trend to move towards ceramic implants because of concerns relating to the release of metal ions. Our customers want to differentiate themselves and will be looking for new materials.

‘The main challenge is that with AMC being mechanically superior, we had to optimise grinding techniques – the harder and stronger the material, the harder it is to machine.’

The Rugby site has also combined ultrasonic technology (see Materials World, January 2008, p15) with conventional diamond-coated tooling for milling and grinding. Due to the low process pressure generated using ultrasonic frequency, more complex, smaller and thinner shapes can be manufactured with better finishes and smaller holes.

This is being applied in medical implants where electronics are increasingly being encased in a ceramic housing, which is more resistant to impact than other materials such as titanium.

Packed up

Research is also in place to improve waste management. The company is exploring reuse of scrap materials in collaboration with other divisions or external manufacturers that require less pure materials. One of the key challenges, however, is to segregate waste streams of multiple grades of ceramics. This is still in its infancy.

Changes have been made, however, in other areas to meet strict environmental criteria. The Rugby site, which is registered to the ISO14001 environmental management standard, uses reusable packaging to meet targets stipulated by the Producer Responsibility Obligations (Packaging Waste) Regulations in the UK. One form of returnable transit packaging is Correx corrugated plastic boxes, which are used to ship components to customers.

In terms of reducing energy and water use, the site has also made headway, but is tightlipped about the specifics. Environmental Officer David Clegg says, ‘The ceramics industry is a high energy usage industry so there is a real benefit to cutting down the use of energy both financially and environmentally. We have looked at the firing process and optimised it, worked on refractory design so we can get less refractory and more product into the kiln, and we have worked on the kilns themselves to improve efficiency. We try to pre-load kilns for quick turnover’.

The future is UK

Essentially, the material and economic challenges are there, but MTC is confident that it is here to stay, with a continued strong presence in the UK, despite recent closures by other manufacturers, particularly in automotives.

Parker concludes, ‘I am a great believer in UK manufacturing. We can take people on from different sectors and train them in our methods. It’s ultimately a self-fulfilling prophecy – we can make teams with the right customers and partners to make sure there are jobs for the younger generation. We have operations in Mexico and China which offer low cost options, but by offering our customers what they need, we believe we have a long future in UK maufacturing’.

Further information:

Morgan Technical Ceramics