Availableonlineatwww.sciencedirect.com SCIENCE c01052e5 t A: applied science ELSEVIER Composites: Part A 37(2006)23-30 Design and optimisation of glass-celsian composites V.Cannillo*, E. Carlier, T. Manfredini, M. Montorsi, C. Siligardia Dipartimento di ingegneria dei Materiali e dell'Ambiente, Universiry of Modena and Reggio Emilia, via Vignoles, 905, 41100 Modena, Italy eCole nale Superieure de Ceramique industrielle, 87065 Limoges, france Received28O October 2004; revised 13 May 2005: accepted 13 May 2005 Abstract The aim of this paper is to fabricate novel glass matrix composites reinforced by means of celsian particulate. In fact, the attractive features of celsian, such as chemical stability and high mechanical resistance, can be favourably exploited in order to obtain enhanced-performance composites with respect to bulk glass. A design of experiments(doE )procedure has been utilized to optimise the fabrication route of glass-celsian composites. This method allowed the determination of the optimal processing conditions for the obtainment of a fully dense material with a good particulate C 2005 Elsevier Ltd. All rights reserved. Keywords: A. Glasses: A. Discontinuous reinforcement; B. Microstructures; C. Statistical properties/methods: Celsian 1. Introduction to toughen glass by means of a particulate reinforcement 5. 6]. However, to the best of authors'knowledge, it is the he objective of this work is to investigate the feasibility first time that celsian is used as reinforcement for glass or of glass matrix composites reinforced with celsian ceramic matrix composites. The idea is to exploit the good particulate. Celsian is a material characterized by great features of celsian to strengthen the glass matrix and obtain hemical stability, high mechanical resistance, high melting a material that has a significantly lower cost than celsian- point and low dielectric constants, and therefore has matrix composites applications for electromagnetic windows or radome a-Celsian has been synthesized starting from zeolites and pplications at high temperatures, packaging for microelec- a commercial frit has been used for the glass matrix, as tronics, high voltage condensers and other electric insulat- described in the following section. These constituents have ing products [1]. Moreover, celsian was also used as matrix been combined in order to produce composites with volume materials for high temperature structural applications in hot fraction of reinforcement in the range 10-30%. Since it is sections of turbine engines [l], in whiskers reinforced well known that sintering conditions may have a great effect celsian-matrix composites [2], in Sic fiber reinforced on the final microstructure, different processing parameters celsian-matrix composites [3] and in mullite/celsia have been tested in order to optimise the final density of the composites [4]. In this work, the possibility to use celsian composites. In fact, porosity may reduce the mechanical as a reinforcement for glass matrix composites is performance of the composites; it is desirable to obtain fully ivestigated. In fact, glass is a low cost material with dense materials, with a even particulate dispersion and a interesting optical, electrical and thermo-insulating proper- good interface between the two phases. In order to optimise the processing route in the shortest times, a doe (design of material. Recently, several papers illustrated the possibility experiments)procedure has been adopted. DOE is a statistically-based method for determining the relationship Corresponding author. Tel: +39 059 205 6240: fax: +39 059 205 between parameters affecting a process and the 6243 such process. The basic idea is that among all possible combinations of parameters, only some of them are tested in 1359-835x/Ssee front matter O 2005 Elsevier Ltd. All rights reserved. order to significantly reduce test time [7, 8]. This method doi:10.1016/j.compositesa.2005.05.037 enables to individuate the most critical parametersDesign and optimisation of glass–celsian composites V. Cannilloa,*, E. Carlierb , T. Manfredinia , M. Montorsia , C. Siligardia a Dipartimento di Ingegneria dei Materiali e dell’Ambiente, University of Modena and Reggio Emilia, via Vignolese, 905, 41100 Modena, Italy b Ecole Nationale Supe´rieure de Ce´ramique Industrielle, 87065 Limoges, France Received 28 October 2004; revised 13 May 2005; accepted 13 May 2005 Abstract The aim of this paper is to fabricate novel glass matrix composites reinforced by means of celsian particulate. In fact, the attractive features of celsian, such as chemical stability and high mechanical resistance, can be favourably exploited in order to obtain enhanced-performance composites with respect to bulk glass. A design of experiments (DOE ) procedure has been utilized to optimise the fabrication route of glass–celsian composites. This method allowed the determination of the optimal processing conditions for the obtainment of a fully dense material with a good particulate dispersion. q 2005 Elsevier Ltd. All rights reserved. Keywords: A. Glasses; A. Discontinuous reinforcement; B. Microstructures; C. Statistical properties/methods; Celsian 1. Introduction The objective of this work is to investigate the feasibility of glass matrix composites reinforced with celsian particulate. Celsian is a material characterized by great chemical stability, high mechanical resistance, high melting point and low dielectric constants, and therefore has applications for electromagnetic windows or radome applications at high temperatures, packaging for microelec￾tronics, high voltage condensers and other electric insulat￾ing products [1]. Moreover, celsian was also used as matrix materials for high temperature structural applications in hot sections of turbine engines [1], in whiskers reinforced celsian–matrix composites [2], in SiC fiber reinforced celsian–matrix composites [3] and in mullite/celsian composites [4]. In this work, the possibility to use celsian as a reinforcement for glass matrix composites is investigated. In fact, glass is a low cost material with interesting optical, electrical and thermo-insulating proper￾ties; however, brittleness limits its usage as structural material. Recently, several papers illustrated the possibility to toughen glass by means of a particulate reinforcement [5,6]. However, to the best of authors’ knowledge, it is the first time that celsian is used as reinforcement for glass or ceramic matrix composites. The idea is to exploit the good features of celsian to strengthen the glass matrix and obtain a material that has a significantly lower cost than celsian– matrix composites. a-Celsian has been synthesized starting from zeolites and a commercial frit has been used for the glass matrix, as described in the following section. These constituents have been combined in order to produce composites with volume fraction of reinforcement in the range 10–30%. Since it is well known that sintering conditions may have a great effect on the final microstructure, different processing parameters have been tested in order to optimise the final density of the composites. In fact, porosity may reduce the mechanical performance of the composites; it is desirable to obtain fully dense materials, with a even particulate dispersion and a good interface between the two phases. In order to optimise the processing route in the shortest times, a DOE (design of experiments) procedure has been adopted. DOE is a statistically-based method for determining the relationship between parameters affecting a process and the output of such process. The basic idea is that among all possible combinations of parameters, only some of them are tested in order to significantly reduce test time [7,8]. This method enables to individuate the most critical parameters Composites: Part A 37 (2006) 23–30 www.elsevier.com/locate/compositesa 1359-835X/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.compositesa.2005.05.037 * Corresponding author. Tel.: C39 059 205 6240; fax: C39 059 205 6243. E-mail address: valeria@unimore.it (V. Cannillo)