Christophe Chaput

Stereolithography for manufacturing ceramic parts

Among the different rapid prototyping technologies, solid freeform fabrication (SFF) is the most suitable for ceramics. Here a stereolithographic technique is presented that allows the usage of pastes composed of ceramic particles dispersed in a photocurable resin for the fabrication of alumina pieces. They exhibit a similar flexural strength than alumina parts made by classical techniques like pressing.

A new custom made bioceramic implant for the repair of large and complex craniofacial bone defects

INTRODUCTION Neurosurgery and Maxillofacial Surgery Departments of Limoges University Hospital Centre have developed a new concept of a custom made ceramic implant in hydroxyapatite (HA) for the reconstruction of large and complex craniofacial bone defects (more than 25 cm(2)). MATERIALS AND METHODS The manufacturing process of the implants used a stereolithography technique that produces implants with three-dimensional shapes derived directly from the scan file of the patients skull without moulding or machining. Eight patients received 8 implants between 2005 and 2008. RESULTS The surgical procedure is simple and fast. The post-operative follow-up was 12 months. No major complications (infection or fracture of the implant) were observed. The cosmetic result was considered satisfactory by both patients and surgeons. CONCLUSIONS These new implants are well suited for reconstruction of large craniofacial bone defects (greater than 25 cm(2)) in adults and children over 8 years.

Ceramic Layer-By-Layer Stereolithography for the Manufacturing of 3-D Millimeter-Wave Filters

Three-dimensional (3-D) ceramic stereolithography has been developed and used to manufacture RF devices using periodic structures. To our knowledge, it is the first time that zirconia and high-performance Ba3ZnTa2O9 ceramics are used with that process to manufacture high unloaded quality factor resonant structures and bandpass filters working in the Ka-band. A theoretical study on the performances of periodic arrangements of high-permittivity structures has been carried out and has led to the manufacture of a high unloaded quality factor cavity and narrow three-pole filter (1% bandwidth) measured at a working frequency of 33 GHz

Narrow Ka Bandpass Filters Made Of High Permittivity Ceramic By Layer-By-Layer Polymer Stereolithography

Electromagnetic bandgap (EBG) concept is used to create cavity by dimensioning a variant cell (or defect) inside a 2D EBG material. Compact high unloaded Q cavity (Qu ~ 2500) and narrow two and three pole filters are designed in Ka band. They are manufactured by layer-by-layer stereolithography and made out of high permittivity yttria-stabilized Zirconia. Measurements of the three pole filter working at 33.45GHz exhibits an 1.05% bandwidth and an insertion loss of 1.7dB. These specifications are close to the theoretical values of 33GHz (1.5% shift in central working frequency) and 0.95% bandwidth

Additive Manufacturing to Produce Complex 3D Ceramic Parts

Attempts to improve the performance of ceramic parts have recently led to advances in their design and in the processes used to tailor these parts. Thus, Additive Manufacturing (AM) technologies, initially developed in the polymers and metals industries, have become of increasing interest for shaping ceramic parts. Among AM techniques, photopolymerization (referred to as stereolithography (SLA) and micro-stereolithography) makes it possible to reach high accuracy that matches the design requirements for new applications of ceramics in a wide range of fields. The development by means of (micro)-stereolithography of complex 3D ceramic parts with improved performance requires the mastering of various parameters linked to the inorganic-organic system involved in this processing route. This paper reports on some recent achievements in the production of ceramics using photopolymerization. Some examples of the work performed at the SPCTS laboratory to produce complex 3D ceramic parts for applications in the fields of information and communication technologies, healthcare and jewellery are presented.

Innovative Shielded High

This letter presents a compact design of a shielded high unloaded Q dielectric resonator. The main interest of this work is the use of the three-dimensional stereolithography process to manufacture innovative ceramic radio frequency devices. Thus, a resonator, its support, and the surrounding cavity is manufactured in one part out of alumina by that process. The measured structure exhibits an unloaded Q of 3900 at 11.88GHz and is free of spurious modes over a 3-GHz range

Q

Innovative resonant cavities based on 2D and 3D Electromagnetic Band Gap crystal properties are presented in this paper. Their geometrical sizes and shapes have been designed and optimized in order to obtain satisfying electrical performances concerning the resonant frequency and the unloaded Q factor. A particular attention has been paid to the Input/Ouput feeding of the structures. The EBG crystals have been designed, optimized and manufactured in one monolithic piece with zirconia or alumina materials. Two specific 3D ceramic stereolithography processes have been developed. Experimental structures have been manufactured and successfully tested compared to the theoretical results.

Dielectric Resonator Made of Alumina by Layer-by-Layer Stereolithography

A design technique based on a shape optimization strategy (topology gradient algorithm) and a 3D ceramic stereolithography process are described in this paper. Our goals are to propose innovative components in terms of electric performances and topologies, by using these two approaches together. Several components have been designed, manufactured and tested with success. An example is given for the design of microwave filters including dielectric resonators.

Electromagnetic band gap millimeter and sub-millimeter 3D resonators manufactured by ceramic stereolithography

A 3D Electromagnetic band gap layer-by-layer crystal is studied in the millimeter wave domain. It has been designed and manufactured by 3D ceramic stereolithography with the ceramic material called zircon. Its particular properties have been used to design a high unloaded quality factor cavity (structural defect) localized within this crystal. This cavity has been measured at 30.5 GHz to demonstrate the concept in the millimeter wave domain. This resonant defect has also theoretically been studied while considering a low loss ceramic material such as BZT. It shows that an unloaded Q close to 10 000 can be obtained at this frequency.