1. A pressure transducer assembly for measuring pressure in high temperature environments, comprising:
a tube having a first opened end and a second opened end,
a pressure transducer mounted on a surface of said tube and extending in to the tube opening to allow said transducer to measure a pressure applied to said tube via said first opened end, said pressure obtained from a pressure source to be monitored, and
a micro-filter mounted and positioned in said second opened end and operative to absorb incoming acoustic waves associated with said pressure source applied to said first opened end.
2. The pressure transducer assembly according to claim 1, wherein said pressure source includes hot gases emanating from a gas turbine engine.
3. The pressure transducer assembly according to claim 2, wherein said front opened end of said tube is mounted within an aperture of a gas turbine engine casing.
4. The pressure transducer assembly according to claim 1, wherein said micro-filter has a plurality of apertures extending from a front surface to a back surface, with said filter positioned and mounted in said second opened end of said tube with said front surface surrounded by said tube wall, wherein pressure waves in said tube are directed to said apertures and travel from said front to back surface of said filter where they are absorbed.
5. The pressure transducer assembly according to claim 4, wherein said apertures have a tapered opening at said front end with said opening at said front end having a larger diameter which tapers into a smaller diameter along a given length of said aperture.
6. The pressure transducer assembly according to claim 5, wherein said front opening of said apertures are conical in cross section.
7. The pressure transducer assembly according to claim 4, wherein said micro-filter is fabricated from glass tubes with said apertures formed by assembling glass tubes of a given diameter in to a cylindrical array.
8. The pressure transducer assembly according to claim 7, wherein said glass tubes have a tapered front opening with a larger diameter at the front which tapers into a smaller diameter.
9. The pressure transducer assembly according to claim 7, wherein said glass tubes prior to forming said filter have an outer diameter between 0.005 inches to 0.020 inches and an inner diameter between 0.004 and 0.015 inches, depending on the frequency of the acoustic waves to be absorbed.
10. The pressure transducer assembly according to claim 1, wherein the temperature of operation is greater than 700\xb0 C.
11. A micro-filter for use in conjunction with a pressure transducer, said pressure transducer having a diaphragm mounted flush with an inner wall of a pressure conducting tube, said tube having a front opened end for receiving a pressure and a back opened end, said filter in combination therewith, comprising:
a cylindrical member having a front surface and a back surface, a plurality of apertures of a given diameter found in said member and directed from said front to said back surface and having a diameter and length selected to absorb lower frequency acoustic waves associated with said received pressure, said member adapted to be mounted at said back opened end of said tube with said apertures aligned parallel to the axis of said pressure conducting tube.
12. The micro-filter according to claim 11, wherein said cylindrical member is fabricated from a plurality of glass tubes each having said given diameter and arrayed in a bundle to form said member.
13. The micro-filter according to claim 12, wherein said glass tubes have a larger diameter front opening which tapers along a partial length of said tube to a smaller diameter.
14. The micro-filter according to claim 13, wherein said glass tube tapers are conical in cross section.
15. The micro-filter according to claim 13, wherein said glass tubes are tapered using a conically shaped coring tool.
16. The micro-filter according to claim 11, wherein said opened front end of said tube is coupled to the inner wall of a gas turbine casing.
17. The micro-filter according to claim 11, wherein said pressure transducer is a piezoresistive pressure transducer.
18. The micro-filter according to claim 1, wherein said apertures have an inner diameter between 0.004 and 0.015 inches.
19. The micro-filter according to claim 12, wherein said glass tubes have an outer diameter between 0.005 to 0.020 inches and an inner diameter between 0.004 and 0.015 inches.
20. The micro-filter according to claim 11, wherein the temperature of operation is greater than 700\xb0 C.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Effect pigments based on glass flakes with a thickness of <1.0 m characterized in that the glass flakes are coated with one or more layers with a high andor low refractive index.
2. Effect pigments according to claim 1, characterized in that the softening point of the glass flakes is >800 C.
3. Effect pigments according to claim 1 or 2, characterized in that the glass flakes are coated with one or more layers of metal oxides, metal suboxides, metal oxyhalides, metal fluorides, metal chalcogenides, metal nitrides, metal sulfides, metal carbides, or mixtures thereof.
4. Effect pigments according to claim 3, characterized in that the metal oxide is TiO2, Fe2O3, TiFe2O5, Ti suboxides, Fe3O4, Cr2O3, Al2O3, SiO2, ZrO2, ZnO, SnO2, CoO, Co3O4, VO2, VO2O3, Sn(Sb)O2 or mixtures thereof.
5. Effect pigments according to claim 4, characterized in that the glass flakes are coated with TiO2, Fe2O3 or a mixture of TiO2 and Fe2O3.
6. Effect pigments according to claim 4 or claim 5, characterized in that the TiO2 is in the rutile modification.
7. Effect pigments according to claim 3, characterized in that the coatings are metal sulfides selected from sulfides of tin, silver, lanthanum, rare earth metals, chromium, molybdenum, tungsten, iron, cobalt andor nickel.
8. Effect pigments according to any of the claims 1 to 7, characterized in that the glass flakes are coated with one or two layers.
9. A method of preparing an effect pigment according to claim 1 which comprises coating of the glass flakes by wet chemical coating, by chemical or physical vapor deposition or electroless plating and optionally calcining the coated glass flakes.
10. Use of the effect pigments according to claim 1 in plastics, coatings, powder coatings, paints, inks, printing inks, glasses, ceramic products, agriculture foils and in cosmetic formulations.
11. Use of the effect pigments according to claim 1 as conductive pigments, as magnetic pigments or as dopants for the laser-marking of papers and plastics.
12. Formulations containing the effect pigments according to claim 1.