ESD dissipative ceramics
View Patent ↗This invention relates to a dense ceramics having ESD dissipative characteristics, tunable volume and surface resistivities in semi-insulative range (10 3 -10 11 Ohm-cm), substantially pore free, high flexural strength, light colors, for desired ESD dissipation characteristics, structural reliability, high vision recognition, low wear and particulate contamination to be used as ESD dissipating tools, fixtures, load bearing elements, work surfaces, containers in manufacturing and assembling electrostatically sensitive microelectronic, electromagnetic, electro-optic components, devices and systems.
1. A method of forming ESD dissipative ceramics comprising the steps of:
(a) forming a mixture comprising from about 85 to 60 vol. % Y-TZP and from about 15 to 40 vol. % ZnO; and
(b) densifying the mixture to at least 95% of the theoretical density by a primary heat treatment.
2. The method of claim 1 , further comprising employing a secondary heat treatment step to increase the density to greater than 99% of theoretical density.
3. A method of forming ESD dissipative ceramics comprising the steps of:
(a) forming a mixture comprising from about 90 to 50 vol. % Y-TZP and from about 10 to 50 vol. % semi-conductive SnO 2 ; and
(b) densifying the mixture to at least 95% of the theoretical density by a primary heat treatment.
4. The method of claim 3 , further comprising employing a secondary heat treatment step to increase the density to greater than 99% of theoretical density.
5. A method of forming an ESD dissipative ceramic component, comprising the steps of:
sintering a composition comprising a base material comprising tetragonal zirconia and a resistivity modifier comprising 5 vol % to about 60 vol % of the base material, the resistivity modifier selected from the group consisting of ZnO, SnO 2 , LaMnO 3 , BaO·6Fe 2 O 3 and mixtures thereof, to form a sintered body; and
hot isostatic pressing the sintered body to form an ESD dissipative ceramic component having a volume resistivity within a rang of 10 3 to 10 11 Ohm-cm.
6. A method of forming an ESD dissipative ceramic component, comprising the steps of:
heat treating a ceramic green body to densify the green body and form a densified component, the green body comprising a base material comprising tetragonal zirconia and a resistivity modifier; the resistivity modifier being selected from the group consisting of ZnO, SnO 2 , LaMnO 3 , BaO·6Fe 2 O 3 ; and adjusting a resisistivity of the densified component by annealing the densified component.
7. The method of claim 6 , wherein the step of adjusting the resistivity is carried out by annealing to change an equilibrium density of charge carriers.
8. The method of claim 6 , wherein heat treating is carried out by sintering.
9. The method of claim 8 , wherein the sintering step is carried out by presurreless sintering.
10. The method of claim 6 , wherein heat treating is carried out by sintering and hot pressing.
11. The method of claim 10 , wherein hot pressing comprises hot isostatic pressing.
12. The method of claim 6 , wherein heat treating is carried out at a first temperature, and annealing is carried out at a second temperature, the second temperature being less than 90% of the first temperature.
13. The method of claim 12 , wherein the second temperature is within a range of about 560° C. to 890° C.
14. The method of claim 6 , wherein the resisitivity is adjusted by at least 25%.