Layered unit provided with piezoelectric ceramics, method for producing the same, and ink jet printing head employing the same

A method of producing a layered unit provided with piezoelectric ceramics having an improved adhesive strength comprising steps in the order of:

• lapping a surface of a first member made of piezoelectric ceramics including lead zirconate titanate in which a total content of alumina (Al2O3) and silicon oxide (SiO2) relative to the piezoelectric ceramics is 0.08 mass % or less, with abrasive grains of silicon carbide having a grain diameter ranging from 5 to 10 μm as free abrasive grains to form a joint surface to be jointed to a second member;
• applying an adhesive agent to at least one of the joint surface of the first member and a surface of the second member to form a joint unit of the first member and the second member;
• and
• curing the adhesive agent while pressurizing the joint unit.

A method of producing a layered unit provided with piezoelectric ceramics having an improved adhesive strength comprising steps in the order of:

• machining a surface of a first member made of piezoelectric ceramics including lead zirconate titanate in which a total content of alumina (Al2O3) and silicon oxide (SiO2) relative to the piezoelectric ceramics is 0.08 mass % or less, with a diamond wheel to which diamond grains having a grain diameter ranging from 5 to 10 μm are attached to form a joint surface of the first member to be jointed to a second member;
• applying an adhesive agent to at least one of the joint surface of the first member and a surface of the second member to form a joint unit of the first member and the second member;
• and
• curing the adhesive agent while pressurizing the joint unit.

A layered unit provided with piezoelectric ceramics comprising:

• a first member made of piezoelectric ceramics;
• a second member which is placed on the first member;
• and
• an adhesive layer which is formed between the first member and the second member to adhere the first member and the second member, wherein
• a joint surface of the first member to be jointed to the second member is formed with a multitude of microprotrusions which have the same composition as crystalline grains of the piezoelectric ceramics and have a height of 0.1 μm or less.

A method of producing a layered unit provided with piezoelectric ceramics having an improved adhesive strength comprising steps in the order of:

• treating a surface of a first member with plasma to form a multitude of microprotrusions thereon so as to form a joint surface of the first member to be jointed to a second member;
• applying an adhesive agent to at least one of the joint surface of the first member and a surface of the second member to form a joint unit of the first member and the second member;
• and
• curing the adhesive agent while pressurizing the joint unit.

An ink jet printing head comprising:

• a base plate;
• an array of ink flow channels each defined by a pair of partition walls each including piezoelectric ceramics made of crystalline grains to constitute a piezoelectric member, the ink flow channels being arrayed on the base plate in a widthwise direction of the ink jet printing head at a certain interval;
• and
• pairs of electrodes each provided at opposing sides of each partition wall to apply a voltage to deform the partition wall, wherein
• a multitude of recesses are formed in a joint surface of the partition wall to be jointed to the base plate by shedding of crystalline grains following breaks in grain boundaries between crystalline grains of the piezoelectric ceramics of the partition wall, a surface area ratio of the recesses relative to a total surface area of the joint surface is set at 50% or more, and the partition wall and the base plate are jointed by an adhesive agent.

An ink jet printing head comprising:

• a base plate;
• an array of ink flow channels each defined by a pair of partition walls each including piezoelectric ceramics made of crystalline grains to constitute a piezoelectric member, the ink flow channels being arrayed on the base plate in a widthwise direction of the ink jet printing head at a certain interval;
• and
• pairs of electrodes each provided at opposing sides of each partition wall to apply a voltage to deform the partition wall, wherein
• a multitude of microprotrusions which are formed in a joint surface of the partition wall to be jointed to the base plate and have the same composition as crystalline grains of the piezoelectric ceramics and have a height of 0.1 μm or less, and the partition wall and the base plate are jointed by an adhesive agent.