Form 9.B Project Summary

Chron:

970966

Proposal Number:

27.01-1370B

Project Title:

Lightweight Mirrors for Optics

Technical Abstract (Limit 200 words)

Silicon carbide (SiC) is a good candidate material

for use as substrates for laser mirrors, solar

collectors and concentrators, astronomical

telescopes and optics in vacuum-ultraviolet and

X-ray regions, since it displays a unique

combination of material properties such as high

elastic modulus, low coefficient of thermal

expansion, high thermal conductivity and low

density besides excellent oxidation and rain erosion

resistance. It is especially suitable for space

applications since it has adequate cryogenic

stability and high resistance to degradation from

atomic oxygen, trapped charges such as electrons

and protons, and high-energy photons. SiC obtained

from sintering, hot pressing or reaction-bonding

process is usually porous and multiphased material,

which does not produce a good optical surface. An

overcoat of CVD Si or SiC is required to eliminate

porosity and increase optical quality. In this Phase I

effort, MMI will synthesize nanoscale Si/SiC

powders using a combination of sol-gel/microwave

plasma processing technique. The nano SiC

powders will be consolidated by microwave

sintering and coated concomitantly with

nanocrystalline silicon powder. Nanocrystalline

silicon particles will enhance densification by liquid

infiltration and provide a homogeneous coating

together with isotropic properties besides

facilitating polishing. The centrifugal float polishing

technique developed by MMI will be used to polish

the lightweight mirror Si/SiC substrate to an optical

surface finish of < 1nm roughness.

Potential Commercial Applications (Limit 200 words)

Space applications with adequate cryogenic stability

and high resistance to degradation from atomic

oxygen, reaction tubes and furnace components in

semiconductor processing, optical materials for

synchrotons, vacuum ultraviolet and x-ray

applications, solar collectors and concentrators.

Name and Address of Principal Investigator (Name,

Organization Name, Mail Address, City/State/Zip)

Zhengui Yao

Materials Modification, Inc.

2929 Eskridge Road, P-1

Fairfax , VA 22031

Name and Address of Offeror (Firm Name, Mail Address,

City/State/Zip)

T.S. Sudarshan

Materials Modification, Inc.

2929 Eskridge Road, P-1

Fairfax , VA 22031