| abstract |
The subject of the invention is a piston of hydraulic brakes, preferably for vehicles, which is made of transformation-hardened mullite ceramics (ZTM-ceramics), which consists of a mullite matrix and dispersed particles of predominantly tetragonal ZrO2. The piston according to the invention protects the brake calipers and the hydraulic fluid in them from overheating, is resistant to rapid temperature changes, and does not break with catastrophic fracture in the event of mechanical and / or thermal overloads. This enables the efficient and safe operation of the braking system during aggressive and long-lasting braking, which is made possible by modern braking systems. Batek according to the invention is prepared by using as a raw material a synthetic mullite powder made by either remelting, sintering, coprecipitation, a sol-gel reaction or any other reaction in the solid, liquid or gaseous state, and a ZrO2 powder which can be doped with Y2O3 or CeO2 or some other oxide stabilizing the tetragonal phase of ZrO2, or a mixture of constituents in appropriate molar ratios or their compounds, together with natural minerals which react during sintering to form mullite and ZrO2 which can be touched with Y2O3 or CeO2 or any other oxide stabilizing the tetragonal phase of ZrO2; Any known dry, wet or plastic molding process, such as pressing, casting, injection molding, extrusion and subsequent machining, may be used to form the blanks, the samples shall be dried or the organic additives required for molding removed after molding, and sinter at temperatures at which this type of ceramic thickens to closed porosity or. to the highest possible relative density. |