This project is concerned with the development of functionally graded materials and structures through the development of a multi-material laser sintering equipment. Once this is achieved this would represent a substantial progress in materials/structures processing when compared to existing man-made materials and equipments. Bio-inspired materials are becoming of increasing interest in many fields of practical applications. In contrast to man-made materials natural materials such as wood, bone, teeth, and shell are composed of materials chemical gradations and hierarchical structuring. This allows them to fulfil and to combine a variety of mechanical and additional functions e.g. combining high stiffness and toughness, benign fracture behaviour, self-adaptability, optical functions, thermal functions, etc. New simulation and production methods intend to allow to structure technical materials similar to the biological templates. Combining the knowledge of natural materials with a newly proposed technique of fabrication of technical materials is the aim of this project. In order to give a step forward in bio-inspired materials/structures development this project intends to design and process: · Multi-material components of metals/alloys and ceramics; · Components with 3D degrees of freedom of chemical composition gradation along its volume; · Hierarquical and cellular structure materials with closed and/or open cells. Although the outputs of the project will cover a wide range of industrial applications such as moulds industry, automotive and aeronautic structural components, electronic devices, etc, this project will focus on development of bio-medical applications namely on dental and hip implants. These would serve as demonstrators of the technological capabilities of the proposed equipment/process. The most important issues to be solved for metallic implant materials are osteolysis and aseptic loosening [1], lack of bioactivity [2], mismatch of the Young's modulus between bone (10–30 GPa) and metallic implant materials (110 GPa for Ti and 248 GPa for CoCrMo alloy) [3], and metallic ion releasing [4]. On the other hand, the real bone cross-section is composed of periosteum, compact bone and spongy bone regions, from outer part to the inner part, respectively. Therefore, in this project, we focused on the requirements on the current implant materials while we inspired from the structure of the real bone. In this context, the main innovative points of the project regarding the design of the components are: · Create an external porosity for osseo-integration (hierarchically cellular open cells) · Create an internal porosity for lower weight (hierarquically celular closed cells) · Create a compositional gradient in longitudinal and radial directions (materials with different functions in different regions) In order to fulfill the previous components/materials requirements the equipment that will be developed to perform it will be a Multi-material Laser Sintering System (MmLSS). New hardware and software systems will be developed to enable both the production of multi-material components or functionally graded components and closed and open cells. The hardware system will comprise a multi-material vat supply system that enables the fabrication of multi-material structures, a dynamic laser processing system and a dynamic building chamber atmosphere. The proposed multi-vat system will be comprised of 5 different material supply vats enabling the material variation during the production of multi-material components. Due to the high variety of powder materials available for laser sintering systems, the building chamber will also be able to vary its controllable sintering atmosphere for each material during production. The fabrication process is based on the projection of an infrared radiation with a wavelength of 1.06 µm with the aid of a scanning system that adjusts its scanning speed according to each powder material specification. The adjustable scanning speed allows adjusting the proper scanning energy depending on each materials characteristic (melting point). The MmLSS system works in an ascendant method sintering the powder from below through a glass window building plate within the building chamber. This process will allow perform hollow cells since the material would remain in the window (see graphical abstract (attach). The system will also involve the development of software to control the apparatus, which works with 3D standard industrial CAD files with appropriate modifications for the production of components of multiple materials or functionally graded. The software will also enable tagging of each building region a specific material for the multi-material production, control the multi-material vat supply system and laser scanning speed for each material.

• Project/scholarship ID

  129123

• Reference

  EXCL/EMS-TEC/0460/2012

• FundRef URI

  http://www.fct.pt/apoios/projectos/consulta/vglobal_projecto.phtml.en?idProjecto=129123&idElemConcurso=7519

• Funder

  FCT - Fundação para a Ciência e a Tecnologia, I.P.

• Funder's country

  Portugal

• Funding program

  5876-PPCDTI

• Funding amount

  453,999.00 €

• Start date

  2013-01-01

• End date

  2015-12-31