Abstract: A method for the manufacture of salt cores is described. The cores are used for the production of cavities in articles which have been made by a pressure casting technique. The cores are resistant to impregnation and fracture during, for example, the application of pressure during squeeze casting. In particular, the method comprises mixing coarse and fine particle salt powders in the ratio from 50/50 to 70/30 coarse/fine, the coarse powder having a maximum particle size of 250 micrometers, the fine powder having a maximum particle size of 25 micrometers. A lubricant, for example, oleic acid is added, possibly the quantity thereof being in the range 0. 1 to 1.0 wt %. A surfactant, such as a silane, also may be added, possibly the quantity thereof being in the range 0.1 to 1.0 wt %. The mixture is pressed to form a core having a density of at least 1.90 g/cm.sup.3 ; and is sintered at a temperature between 650.degree. C. and 775.degree. C., for a time in the range 15 minutes to 1 hour.

Abstract: A method of making a siliconized silicon carbide article by(i) injection-molding a mixture which comprises a major proportion of silicon carbide particles and a minor proportion of organic binder material, the mixture being flowable under heat and pressure,(ii) heating the molded article thus formed so as to remove the organic binder material from it and obtain a porous silicon carbide body containing elemental carbon, and(iii) impregnating the porous body with molten silicon to convert said carbon to silicon carbide which binds together the original silicon carbide particles,in which step (iii) is carried out by utilizing as a conduit for said molten silicon the sprue that is formed integrally with the injection-molded article in step (i).The method avoids excessive contact between the surface of the porous intermediate shaped body and molten silicon employed for siliconization, and so reduces the possibility of damage to that body while it is in the weakly bonded state.

Abstract: An endoprosthetic bone component is produced from parts respectively having a projection and cavity engaged in a mutual clearance fit, and a third part of plastics material located in the space of such fit, the space and third part being dimensioned to inhibit ejection of the latter and to lock the two parts against mutual articulation during post-operative use. Normally the space and third part will be of generally uniform thickness overall which is small compared to that of the projection. Also the projection and cavity are preferably of uniform cross-sectional shape over at least major portions thereof. Typically the two parts will be of different materials, such as ceramic and metal, suited respectively to articulation and bone fixation roles.

Abstract: Pistons for internal combusion engines are described. The pistons comprise a crown component and a skirt component wherein the crown component consists of an iron or nickel based alloy annular portion having fitted directly therein a ceramic insert, the crown component being joined to the skirt component by an annular composite laminated member of steel and aluminium alloy the steel of the laminated member being energy beam welded to the annular portion of the crown component and the aluminum alloy of the laminated member being energy beam welded to the skirt component there being after welding a sealed, hollow, annular chamber disposed at the junction between the crown component and the skirt component. Embodiments are described having ceramic inserts of silicon nitride and including combustion bowls.