1.C.7.Ceramic powders, ceramic-"matrix" "composite" materials and 'precursor materials', as follows:

a. Ceramic powders of titanium diboride (TiB₂) (CAS 12045-63-5) having total metallic impurities, excluding intentional additions, of less than 5,000 ppm, an average particle size equal to or less than 5 µm and no more than 10% of the particles larger than 10 µm;
b. Not used since 2016
c. Ceramic-"matrix" "composite" materials as follows:
1. Ceramic-ceramic "composite" materials with a glass or oxide-"matrix" and reinforced with any of the following:
a. Continuous fibres having all of the following:
1. Being made from any of the following materials:
a. Al₂O₃ (CAS 1344-28-1); or
b. Si-C-N; and
2. Having all of the following:
a. Tensile strength equal to or greater than 700 MPa at 1,273 K (1,000°C); and
b. Tensile creep resistance equal to or less than 1% creep strain at 100 MPa load and 1,273 K (1,000°C) for 100 hours.
b. Fibres having all of the following:
1. Being made from any of the following materials:
a. Si-N;
b. Si-C;
c. Si-Al-O-N; or
d. Si-O-N; and
2. Having a "specific tensile strength" exceeding 12.7 x 10³ m;
c. 2. Ceramic-"matrix" "composite" materials with a "matrix" formed of carbides or nitrides of silicon, zirconium or boron;
N.B. For items previously specified in 1.C.7.c., see 1.C.7.c.1.b.
d. Not used since 2016
N.B. For items previously specified in 1.C.7.d., see 1.C.7.c.2.
e. 'Precursor materials' specially designed for the "production" of materials specified in 1.C.7.c., as follows:
1. Polydiorganosilanes;
2. Polysilazanes;
3. Polycarbosilazanes;
Technical Note
For the purposes of 1.C.7., 'precursor materials' are special purpose polymeric or metallo-organic materials used for the "production" of silicon carbide, silicon nitride, or ceramics with silicon, carbon and nitrogen.
f. Not used since 2016
N.B. For items previously specified in 1.C.7.f., see 1.C.7.c.1.a.