The effects of P/Al ratio and Cr/Al ratio on the phase composition

microstructure

mechanical properties and dielectric properties of quartz fiber-reinforced phosphate composites were investigated. The results show that the phase composition of the phosphate matrix is mainly composed of Berlinite phase

low-temperature quartz type AlPO

4

and  unreacted α–Al

2

O

3

and the composition ratio and microstructure of the matrix phase are influenced by the P/Al ratio and Cr/P ratio. When P/Al=4.1 and Cr/P=0.04

the composites have the best mechanical properties

with t

ensile strength of 108.6 MPa

bending strength of 135.3 MPa and fracture toughness K

ⅠC

of 6.6 MPa·m

1/2

and the composites exhibit the plastic fracture characteristics of weak bonding interface. It is analyzed that at this time the matrix contains more Al(H

2

PO

4

)

3

phase with good bonding properties

and the matrix exhibits a smooth planar-like structure

which is conducive to the formation of a complete and continuous good interfacial layer between the matrix and the fiber. In addition

the dielectric properties of the materials are greatly affected by the Cr content

except for Cr/P=0.08 materials

the dielectric properties of the prepared materials can meet the performance requirements of high-temperature wave-transparent materials

and have a broad application prospect.