Abstract: A friction engaging device, such as, for example a braking disc and a friction couple, brake disc/pad are disclosed. The friction engaging device is a carbon-ceramic composite comprising a carbon fibre network and a filler comprising silicon carbide. One device comprises, by weight, from 35-50% carbon fibre, 14-30% free carbon, 10-28% silicon carbide, 5-14% silicon and 5-14% silicon oxide. Also disclosed is a method of producing a friction engaging device in which a carbon-carbon composite comprising 10 to 60% by weight of a carbon fiber network and from 40 to 90% by weight free carbon is impregnated with silicon under conditions such that substantially all of the carbon fibre network remains as carbon fiber, and a proportion of the free carbon present in the volume is converted within the volume to silicon carbide by reaction with the silicon.

Abstract: A friction pad for a brake assembly including a backing plate having attached to it a pad of friction material containing at least 50% by weight of a ceramic material present in the form of relatively coarse particles of diameter 0.3 mm to 4 mm and a synthetic resin binder, together with a minor amount of a graphite lubricant and a minor amount of a ceramic material in the form of relatively fine particles in the size range 1 to 30 microns.

Abstract: A cutting tool tip is formed at least at a cutting edge of the tip from a ceramic product consisting essentially of at least 75% by volume of a single phase compound having an expanded .beta.-phase silicon nitride lattice and having the general formula Si.sub.6-z Al.sub.z N.sub.8-z O.sub.z, where O<z.ltoreq.5, together with a second phase containing a metal from the list yttrium, lanthanum, cerium and scandium, or other rare earth metal.

Abstract: A starting aid for a combustion engine comprises a hollow elongated body and a refractory electrical heating element mounted in the body at one end thereof. Formed in said one end of the body are one or more holes through which, in use, the heating element can be exposed to the combustion mixture of an engine. In addition, the body is formed with at least one exhaust aperture which is spaced from the heating element in the direction of the other end of the body and which permits the escape of gases entering the body through said one or more holes. Extending through the body and electrically connected to the heating element is an electrode rod for supplying heating current to the heating element to raise its temperature. The electrode rod includes two relatively movable parts which are mechanically connected by resilient means to maintain the heating element in compression against said one end of the body and which are electrically connected by a flexible braid.

Abstract: A method of producing a ceramic product which comprises the step of forming a powder mixture consisting essentially of a first component consisting of compounds containing the elements silicon, aluminum, oxygen and nitrogen in proportion such that the ratio of the total number of silicon and aluminum atoms to the total number of oxygen and nitrogen atoms lies in the range 0.735 to 0.77 and such that said compounds react together during the subsequent sintering process to produce a single phase ceramic material obeying the general formula:Si.sub.6-z Al.sub.z O.sub.z N.sub.8-zwhere z is between 0.38 and 1.5, and between 0.1 and 10% by weight of a second component in the form of an oxide of at least one of the further elements yttrium, scandium, cerium, lanthanum and the metals of the lanthanide series. The mixture is then sintered in a protective environment at a temperature between 1600.degree. C and 2000.degree.