14 May 2018

Metal matrix composite research with the Autotouch | Spectroscopy Solutions

Composite materials with hybrid properties are now common as engineering materials. In the form of glass-fibre reinforced plastics, carbon fibre composites, and laminated construction products such as plywood, composite materials have been commonplace for decades.

For application critical components such as piston heads and connecting rods in internal combustion engines, jet engine turbine blades, and highly stressed bearings and other structural parts, composite materials can offer improved strength and wear resistance for similar or lesser weight and bulk to other materials.

New progress in composite material research

In recent years, the search for new composite materials has come to include ceramic and metal matrix composites. At Dublin City University, researchers led by Professor Dermot Brabazon have investigated several such materials. Aluminium and other metal powders have been combined with ceramic reinforcements such as silicon carbide, but also novel nano-reinforcements. Metallic materials reinforced in this way are known as Metal Matrix Composites (MMCs). 

These materials, which have applications in structural, electrical and electronic engineering, as well as in the production of consumer products, are formed by careful preparation and mixing of powders with their reinforcements, compacted under high pressure using a hydraulic press, then sintered in an inert atmosphere for several hours to produce the final engineered product.

Mixing and compressing powdered graphene

Professor Brabazon’s team have investigated carbon nanotubes (CNTs), graphene, and graphene oxides as reinforcing materials. Graphene is a material promising exceptional physical and electrical properties. It must be thoroughly dispersed within the aluminium matrix, which can be achieved via careful control of the mixing process.

Read the full application note on how the Autotouch hydraulic press was used to compact aluminium graphene composites.

The mixed powders are then transferred to one of Specac’s evacuable pellet dies for compaction in the Atlas® Autotouch 40T press. Pressures of up to 780 MPa are achievable with this combination of die and press. The programmable functionality of the press ensures repeatable control of the pressure level, ramp rate, and dwell time. The ability to store multiple programmes enables rapid optimisation of the compacting process parameters through a design of experiments method.

This is important, because the properties of both the un-sintered (‘green’) compact and the resulting composite are dependent upon the compaction parameters. Failure to provide accurate control over compaction leads to high levels of inter-sample variation in compaction efficiency with corresponding variation in the physical strength of the composite materials produced, both undesirable properties in real-world engineering materials.

Metal additive manufacturing research

Another major research avenue for Professor Brabazon’s group is metal additive manufacturing. This is akin to 3D printing, but with metal powders. 3D printed products are built up by adding layer upon layer (hence the term additive manufacturing. Layers are constructed by applying fine metallic powders (possibly pre-mixed with reinforcing elements) in a pattern corresponding to a section through the final product; the layer is compacted slightly, then sintered using a high-powered laser to produce a solid metal form onto which the following layer may be applied. Additive manufacturing is more efficient than subtrative manufacturing, producing less waste material.

Subtractive manufacturing vs. additive manufacturing

Though this is a very different application, the basic steps of powder mixing, compaction, and sintering are similar, and much of the work on MMCs is applicable to studying metal additive manufacturing.

Get in touch: Collaborate with Specac

Through working with Specac, Prof. Dermot Brabzon and his team's work has been championed via video, application note and online editorial. The research will be shared internationally via various promotional channels. Are you working in a field that uses, or could use, our FTIR, polarizer, heated platen or hydraulic pressing equipment? Do you want your work reported to a wider audience?

Get in touch! We want to collaborate with end-users and promote the various fields our equipment is being used for. We are proud of the work you do with our tools and accessories. Read the details below and email us, we’ll be in touch as soon as possible. We are offering end-users the chance to:

  • perform research with Specac’s assistance and have findings cited in an application note
  • be interviewed, to discuss the importance of their work, the challenges they have faced and more
  • be promoted throughout the industry, via Specac’s marketing channels; such as email, social media, print advertising and more

To promote your research with us, please contact collab@specac.co.uk with a simple brief, detailing:

  • what your work involves
  • what equipment you currently/can use
  • why your work is important

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