Method for joining a ceramic friction element to a piezoceramic element

A method of joining a ceramic friction element (11) to an element of piezoceramic material defining a piezoelectric element (1), said piezoelectric element (1) comprising at least one excitation electrode (2) and at least one general electrode (3) spaced from the at least one excitation electrode (2), and between said excitation electrode (2) and said general electrode (3) at least a portion of the piezoceramic material of said piezoelectric element (1) is disposed, said method comprising the following process steps:

• Step 1:
• Preparation of a low-melting glass mass (12);
• Step 2:
• Disposing the low-melting glass mass (12) between a joining surface (10) of the friction element (11) and a contact surface (9) of the piezo element (1);
• Step 3:
• Applying a pressing force and pressing the joining surface (10) of the friction element (11) and the contact surface (9) of the piezoelectric element (1) against one another with the low-melting glass mass (12) arranged therebetween and maintaining the pressing force for all subsequent process steps;
• Step 4:
• Heating the piezoelectric element (1) and the friction element (11) to a defined temperature above the Curie point of the piezoceramic material of the piezo element (1) and above the melting point of the low-melting glass mass (12);
• Step 5:
• After reaching the defined temperature of the piezoelectric element (1) and the friction element (11) and while maintaining the defined temperature, applying an electric polarization voltage Up to the electrodes (2, 3) of the piezoelectric element (1) so that an electric field Ep polarizing the piezoceramic material is generated in the piezoceramic material between the electrodes (2, 3), and maintaining the electric field Ep for a defined period of time;
• Step 6:
• Cooling the piezoelectric element (1) and the friction element (11) while maintaining the polarizing electric field Ep below the Curie point, and, after falling below the Curie point, removing the electric polarization voltage Up applied to the electrodes (2, 3);
• Step 7:
• Cooling the piezoelectric element and the friction element to room temperature without any electric voltage being applied to the electrodes (2,3).