1964_IMPORT_AND_EXPORT_(STRATEGIC_COMMODITIES)_REGULATIONS — Page 144

G 144

CAP. 60]

Import and Export (Strategic Commodities) Regulations

(1988 Ed.

[Subsidiary]

IL 1734

IL 1746

Single or complex non-composite oxides, borides, carbides or nitrides of silicon, aluminium, boron, zirconium or tantalum, except:

(i) Single oxides of silicon, boron, aluminium or tantalum;

(ii) Single or complex borides of silicon; and

(iii) Single or complex borides or carbides of aluminium;

Technical Notes:

1.

2.

For the purpose of this item, "high purity" is defined as a total metallic impurity, excluding intentional or desired additions, of less than—

(a) 1000 ppm for single oxides or single carbides;

(b) 5000 ppm for complex compounds, single borides or single nitrides. "Fine powders with uniform particle size distribution" are defined as powders with at least 90 per cent of the particles being less than or equal to 10 micrometres, and the average particle size being less than or equal to 5 micrometres.

(For zirconia, these limits will be micrometres and 1 micrometre respectively.)

Notes:

1.

2.

3.

For compounds of thorium or hafnium, see also Items A.2 and A.8 on the Atomic Energy List.

For compounds of zirconium, see also Item A.4 on the Atomic Energy List. For compounds of tantalum, see also Item IL 1760.

(b) Non-composite ceramic materials, in crude or semi-fabricated form, having compositions of the base materials embargoed by sub-item (a) above;

(c) Granular or fibrous ceramic-ceramic composite materials, containing finely dispersed particles or phases or any non-metallic fibrous or whisker-like materials, whether externally introduced or grown in situ during processing, where the following materials form the host matrix:

(1) All oxides, including glasses;

(2) Carbides or nitrides of silicon or boron;

(3) Borides, carbides or nitrides of zirconium, hafnium or tantalum;

(4) Carbon; or

(5) Any combination of the materials enumerated in (1) to (4) above;

(d) Precursor materials, i.e. special-purpose polymeric or metallo-organic materials for producing any phase or phases of the materials covered by sub-items (b) or (c) above, as follows:

(1) Polycarbosilanes and polydiorganosilanes (for producing silicon carbide);

(2) Polysilazanes (for producing silicon nitride); or

(3) Polycarbosilazanes (for producing ceramics with silicon, carbon and nitrogen components);

Low density rigid, carbon-bonded, fibrous or non-fibrous carbon thermal insulating materials having all of the following characteristics---

(a) a capability of operating at temperatures greater than 2273K (2000°C);

(b) A density greater than 100 kg/m3 and less than 300 kg/m3;

(c) A compressive strength greater than 0.1 MPa and less than 1.0 MPa;

(d) A flexural strength greater than 1.0 MPa; and

(e) A carbon content of greater than 99.9% of total solids.

Polymeric substances, as follows, and manufactures thereof (a) Polyimides (including maleimides);

Note:

This sub-item is not intended to cover fully cured polyimide or polyimide-based film, sheet, tape or ribbon having a maximum thickness of 10 mils (0.010 inch or 0.254 mm) whether or not coated or laminated with heat- or pressure-sensitive resinous substances of an adhesive nature, which contain no fibrous reinforcing materials and which have not been coated or laminated with carbon, graphite, metals or magnetic substances.