The influence of fiber coating conditions on the mechanical properties of alumina/alumina composites

Abstract

Alumina bers as a form of fabric cloth are slurry coated by a vacuum enhanced dipcoating (VEDC) method for the reinforcement of an alumina matrix. Three kinds of precursors including YPO 4 , CePO 4 and LaPO 4 are prepared and applied to the coating of alumina cloth. SEM observation shows that the bers in the bundle are uniformly coated by this method. The coated bers are debonded from the matrix during fracture of the composites. Mechanical properties of these composites using the vacuum enhanced dip-coated bers are affected by the properties of coating slurry, including concentration and pH value. The three kinds of coating have shown no signi cant difference when they are coated under the same conditions. Increase of the concentration of the coating slurry causes increase of the bulk density of the composites, while the optimum coating thickness corresponding to the highest maximum fracture strength is obtained by the medium slurry concentration. When pH of the coating slurry is nearly neutral, the coating becomes uniform and the highest maximum strength as well as the highest density of the composites are achieved.

Effects of Sintering Condition on Mechanical Properties of Monazite-Coated Alumina-Fiber/Alumina-Matrix Composites Fabricated by Hot-Pressing

“…In respect of fabrication of alumina/alumina composites with high volume fraction of monazite-coated ®bers, fabric cloth coating technique was developed, 22) and uniform coating of all ®bers in bundle or cloth has been achieved. Thus, examination of composites reinforced by monazite-coated ®bers is possible.…”

“…Details of the ®ber coating process was described elsewhere, 22) and was simply mentioned as follows. Monazite was synthesized by the reaction of La(NO 3 ) 3 solution with H 3 PO 4 in the same molar ratio.…”

Fabrication alumina fibers reinforced alumina matrix composites using monazite as interface

“…Basic preparation of these sheets has been reported elsewhere [16], and simply described as follows. Polyvinyl butyric (PVB, Sekisui Chemical, Japan) as binder and dioctyl adipate (Wako Pure Chemical, Japan) as a plasticizer were dissolved into ethanol and stirred for 24 h at 40 • C. α-Al 2 O 3 powder (99.99 wt%, 0.24 µm, Taimei Chemical, Japan) and ethanol were mixed with the addition of a little amount of HNO 3 and then added to the well-dissolved solution of the above prepared binder/ plasticizer.…”

ホットプレス法により作製した LaPO₄ 被覆アルミナ繊維/アルミナマトリックス複合材の 高温機械的性質

“…15) The uniform coating of all fibers in bundles or cloths to achieve better pseudoductility of the composites has been achieved. 16) Furthermore, the effects of fabrication conditions on the roomtemperature (RT) mechanical properties of composites using coated fibers were examined.…”