C-i-l, Inc.

Canadian Patents and Development Limited/societe Canadienne Des Brevets

Canadian Industries, Ltd.

Corporation De I'ecole Polytechnique

Jitka Kirchnerova

Anthony C Edmonds

Danilo Klvana

James M Skeaff

Terrence C Matts

Errol L Falconer

Joseph R Pare

Christopher W Bale

The new preparation process for making fine high specific surface ceramic powders suitable as catalysts or precursors for ceramics uses lanthanum (or other rare earth lanthanide) oxide as one of the precursors. The oxide is mixed with water to form a liquid slurry, whereby it is transformed to the hydroxide by reaction with water. The resulting hydroxide slurry, which can be milled to reduce the particle size and to speed up the reaction, is then combined, while stirring vigorously to assure homogenous mixing, with a solution of required amount of remaining metal nitrate precursors, for example strontium and cobalt nitrates. The reaction between lanthanum hydroxide and transition metal nitrates produces a colored (color depending on the transition metal) slurry consisting of metal hydroxides suspended in aqueous nitrate solution with pH&gt;2. This perovskite precursor slurry is spray-frozen and freeze dried. The freeze-dried material is transformed to perovskite by slow controlled calcination at temperatures above 550.degree. C. For example calcination 12 h at 585.degree. C. and subsequently 4 h at 620.degree. C. produces nearly phase pure perovskite having specific surface area of &gt;10 m.sup.2 /g, depending on the composition. The perovskite precursor slurry can alternatively be processed first by spray-drying (instead of spray-freezing/freeze-drying) and subsequent calcination.

Process of making fine ceramic powders from aqueous suspensions

A potentiometric electrochemical sensor for detecting gaseous concentrations of arsenic oxides or arsenic-bearing species at elevated temperatures. The sensor is comprised of: an ionically conducting solid state membrane which may be made of silver zirconium arsenate, sodium beta-alumina or silver beta-alumina; a reference electrode which may be silver wire packed in silver powder; and a working electrode which may consist of a platinum mesh electrode or a silver wire exposed to the arsenic oxide-bearing gas. The probe is responsive to arsine [AsH.sub.3 ] concentrations in the range 5-1000 ppm in oxidizing gases, such as air, which have been raised to the temperature range 600.degree.-900.degree. C. The compound silver zirconium arsentate is also novel.

Solid state arsenic probe for use in pyrometallurgical processes

An improved method of gassing an aqueous slurry explosive composition with an inorganic nitrite gassing agent is provided. The method makes use of a thiocyanate ion-containing material in the composition as a gassing accelerator. The presence of the thiocyanate ion produces improved rate and quantity of gas generation even under low temperature where gas generation is normally retarded.

Gelled aqueous slurry explosives containing gas bubbles

A slurry explosive composition is provided which has improved water resistance and thermal stability and resists segregation. The composition consists of an inorganic oxygen-supplying salt, a liquid carrier or solvent for the salt, a solid or liquid fuel and, as a thickener a sulfonated guar gum derivative.

Explosive compositions containing sulphonated guar gum derivatives

Growing community of inventors

Montreal, Canada

Jitka Kirchnerova