Silica/Silica Composites Through Electrophoretic Infiltration - Effect of Processing Conditions on Densification of Composites

Abstract

Ceramic matrix composites are high performance, high temperature materials of scientific as well as technical interest. During the last decade there has been great interest in development of oxide composites for structural as well as electrical applications. Silica/silica composites have been developed using electrophoretic infiltration. Matrix was derived from silica sol and colloidal silica sol having different process routes, solid content (24% -35%), pH (2 -3.5) and viscosity (55 -70 mpoise). The effect of densification parameters such as applied voltage, infiltration time, thickness of preform, viscosity, etc., have been studied and discussed.Composites processed at lower potential difference and under constant current density conditions yield better matrix microstructure and particle bonding, as well as interlaminar bonding. The composites fabricated with colloidal silica sol exhibit 60% sintered density.

Fabrication technologies for oxide–oxide ceramic matrix composites based on electrophoretic deposition

“…This behaviour is in broad agreement with extensive evidence in the literature on the high versatility of the EPD technique to infiltrate 2D and 3D fibre performs with ceramic (nano)particles. 15,16,[18][19][20][21][22][23][24][25] The SEM micrographs in Fig. 7 compare the microstructures of the EPD-infiltrated Nextel TM 720 fibre mat in "green" and sintered state.…”

“…and fibres. 15,16,[18][19][20][21][22][23][24][25] The main advantages of EPD over a conventional slurry route are the reduced processing times and improved control over green body microstructure. 15,16 Aqueous or non-aqueous suspensions of ceramic (nano)particles are usually considered for forming the matrix, and both conductive (e.g.…”

“…Nextel TM ) fibres have been used as reinforcement. [18][19][20][21][22][23][24][25] In the case of non-conductive fibres, the fibre weave is placed in front of the deposition electrode and the ceramic deposit forms on the electrode and grow around and through the fibre mat. 15,25 A schema of a typical EPD cell, commonly used for the infiltration of single non-conductive fibre mats, is shown in Fig.…”

Preparation of a thermal insulating material using electrophoretic deposition of silica particles

“…Electrophoretic deposition (EPD) is the process by which charged particles in a suspension medium move under an applied field to an oppositely charged electrode and coagulate to form a stable deposit [1]. EPD has been widely applied to fabricate matrices, fibres and coating [2,3,4]. This paper presents the use of electrophoretic deposition to fabricate different density fumed silica particle agglomerates with high thermal performance.…”

Continuous silica fiber reinforced silica composites densified by polymer-derived silicon nitride: Mechanical properties and microstructures

“…Chen et al developed a vacuum-assisted liquid phase infiltration process with suspension of silica and the addition of a non-ionic surfactant to enhance the densification of 3D SiO 2f /SiO 2 materials, resulting in a density of 1.65 g/cm 3 with a flexural strength of about 75 MPa [3,4]. Additionally, an electrophoretic infiltration process of colloidal silica sol was applied to fabricate SiO 2f /SiO 2 composites, which showed a low density of 1.50-1.65 g/cm 3 strength just about 25-60 MPa due to the sensitive surface of glass fibers [5,6]. Although the density and strength of SiO 2f /SiO 2 composites can be improved by some organic polymers (such as silicone) infiltration method, the residual free carbon in these polymers will decrease the microwave transparence efficiency under high temperatures.…”