CVD DIAMOND BURRS FOR ODONTOLOGICAL AND RELATED USES

Abstract: The object of the invention is the process of obtainment of CVD diamond burrs, mills and files of odontological and related uses, for boring, abrading and machining teeth, glass, ceramics, metals, etc. The patent includes any CVD diamond deposition method and gas mixture. The CVD diamond may be deposited as a thin or thick film directly on the tool stick material, or may be deposited as a freestanding film on a substrate material for posterior joining to the tool stick, or the tool stick may be prepared by the deposition of diamond powder by any process, before a direct deposition of the CVD diamond

Description: CVD DIAMOND BURRS FOR ODONTOLOGICAL AND RELATED USES. This invention is related to the technology of Chemical Vapor Deposition (CVD) diamond growth. This is a subject of intense interest, not only due to basic research, but mainly to the many possible technological applications. Some of its superior properties make diamond the material of choice for many applications. Some CVD growth techniques have been developed at Instituto Nacional de Pesquisas Espaciais (INPE) and the present invention is a result of this development. The object of this patent is fundamented in the growth of thin and free standing CVD diamond films. These diamond films may be directly deposited and/or brazed on pins of stainless steel or any other material, to be used as burrs, mills and files in odontological and related work. It is, also, object of this patent the obtainment of burrs, mills and files from the deposition of CVD diamond on any kind of material with diamond powder impregnated by any process. For example, CVD diamond may be deposited on conventional odontological burrs, obtained from electrodeposited and/or brazed diamond. The diamond films may be obtained by the Hot Filament Chemical Vapor Deposition (HFCVD) or any other CVD technique. The HFCVD technique is particurlaly suitable due to its simplicity and low cost. Therefore we describe the obtainment of thin and free standing films based on the HFCVD technique. To use other growth techniques it is necessary to adapt the growth conditions to the appropriate activation method. The procedure to obtain burr from thin and freestanding diamond films with poor adherence with the final burr stick is as follows: a) preparation of substrate pins of a material suitable for diamond growth, molybdenum for example. The diameter and the length of such pins depend on the growth parameters and growth method. The upper end must be prepared to have the final form of the burr tip; b) deposition of the diamond film on the upper end of the substrate pins prepared in the previous item. The growth conditions in the reactor for the deposition of the freestanding diamond tip must be adjusted in order to obtain the largest grain size. The boring and abrading capabilities depend on the grain size of the burr tip. c) dissolution of the substrate pins in acid solution to release a freestanding diamond tip; d) laser trimming of the diamond tip, or any other trimming method, to eliminate its fragile end; e) brazing of the diamond tip on the final burr stick, made of stainless steel or any other suitable material, to obtain the final burr form. The excess of brazing alloy is removed to free the diamond cutting surface. If the final burr stick is suitable for diamond growth with good film adherence, the procedure is as follows: a) preparation of the burr stick in its final form; b) preparation of the burr stick end surface to assure a good adherence of the diamond film; c) deposition of a thin or thick diamond film directly on the burr stick end. Both cases may use the same diamond growth system during the deposition procedure. Figure 1 shows a schematic diagram for a HFCVD diamond growth reactor. The method consists in flowing a gas mixture appropriate for diamond growth, for example a mixture of methane highly diluted (0.1 - 4%) in hydrogen, through the reactor: (1). The hot filament is located at the proper distance from the substrates (3) . Each gas component of the mixture may be stored (4) and controlled independently with flow controllers (5) . A premixed gas mixture may also be used. The reactor internal pressure may be conveniently controlled with needle valves (6), a vacuum pump (7), and an absolute pressure meter (8) . The filament and substrate temperatures are monitored by an optical pyrometer (9) and a thermocouple, respectively. The film thickness may be controlled by the growth time. With such reactor is possible to grow diamond on various substrate forms depending on the desired application. For the case of odontological burrs the substrate may be small pins of which the upper ends are prepared to obtain the desired burr tip form. If the burr stick material is suitable for adherent film growth it is possible to grow a thin diamond film directly on the burr tip. Otherwise, if the burr stick is not suitable for diamond growth, it is necessary to grow a freestanding film on an appropriate substrate, dissolve the substrate, trim the fragile end of the diamond tip, and braze it on the burr stick. The HFCVD system is very convenient for scale production of such CVD diamond tips. An adequate substrates' holder may maximize the production efficiency of a single reactor. Figure 2 shows an example of an appropriate substrate holder positioned relative to the filament. A spiral filament (1) and the substrate holder (2) are placed in an adequate position to keep the same distance from the various pin substrates (3) . The number of pin substrates per reactor may be in the order of several tens for filaments only a few centimeters long. The substrate holder may have through holes (4) conveniently distributed to allow gas flow in the reactive region.

Claims: Patent Claims 1. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a thin diamond film on burrs made in any format and of any material, obtained by the deposition method of hot filament assisted chemical vapor deposition. 2. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a freestanding diamond film on burrs made in any format and of any material, obtained by the deposition method of hot filament assisted chemical vapor deposition. 3. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a thin diamond film on burrs made in any format and of any material, obtained by the deposition method of microwave or radio frequency plasma assisted chemical vapor deposition. 4. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a freestanding diamond film on burrs made in any format and of any material, obtained by the deposition method of microwave or radio frequency plasma assisted chemical vapor deposition. 5. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a thin diamond film on burrs made in any format and of any material, obtained by the deposition method of arcjet plasma assisted chemical vapor deposition. 6. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a freestanding diamond film on burrs made in any format and of any material, obtained by the deposition method of arcjet plasma assisted chemical vapor deposition. 7. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a thin diamond film on burrs made in any format and of any material, obtained with any gas mixture, including mixtures in any proportion of methane (CH-,) diluted in hydrogen (H 2 ) , for any of the deposition methods in the patent claim 1 - 6. 8. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of a freestanding diamond film on burrs made in any format and of any material, obtained with any gas mixture, including mixtures in any proportion of methane (CH 4 ) diluted in hydrogen (H 2 ) , for any of the deposition methods in the patent claim 1 - 6. 9. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the joining of a freestanding diamond tip of any format on a burr stick of any material. The diamond tip may be grown on any substrate material by any of the deposition methods and using any of the gas mixtures cited in patent claim 1 - 8. The joining of the diamond tip to the burr stick may be made with any kind of welding or brazing method with any brazing alloy. 10. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the use of any of the processes and methods described in patent claims 1 - 9 for the obtainement of burrs, drills, mills and files for boring, abrading, drilling and machining of glassy materials. 11. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the deposition of thin or thick diamond films on sticks of any material prepared by the deposition of diamond powder by any process. The diamond film may be deposited with any of the methods described in patent claim 1 - 8. The diamond particles of the diamond powder may size from sub- micrometric to milimetric range and are used to enhance nucleation and adherence of the diamond film on the stick material. 12. CVD diamond burrs for odontological or related boring and abrading applications, characterized by the use of any of the processes and methods described in patent claims 11 for the obtainement of burrs, drills, mills and files for boring, abrading, drilling and machining of glassy materials.

Inventors: BARANAUSKAS VITOR, CARNEIRO VALERA MARCIA, CORAT EVALDO JOSE, DEL BOSCO EDSON, FERREIRA LEITE NELIA, TRAVA AIROLDI VLADIMIR JESUS, VILCHE PENA ANGEL FIDEL, BARANAUSKAS, VITOR, CARNEIRO VALERA, MARCIA, CORAT, EVALDO, JOSE, DEL BOSCO, EDSON, FERREIRA LEITE, NELIA, TRAVA AIROLDI, VLADIMIR, JESUS, VILCHE PENA, ANGEL, FIDEL
Applicants: BARANAUSKAS VITOR, CARNEIRO VALERA MARCIA, CORAT EVALDO JOSE, DEL BOSCO EDSON, FERREIRA LEITE NELIA, INST NACIONAL DE PESQUISAS ESP, TRAVA AIROLDI VLADIMIR JESUS, VILCHE PENA ANGEL FIDEL, BARANAUSKAS, VITOR, CARNEIRO VALERA, MARCIA, CORAT, EVALDO, JOSE, DEL BOSCO, EDSON, FERREIRA LEITE, NELIA, INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS, TRAVA AIROLDI, VLADIMIR, JESUS, VILCHE PENA, ANGEL, FIDEL
Application year: 1996
Main classification: C23C16
IPC codes: A61C3, C23C16