Abstract: Apparatus for cooling bleed air on an aircraft may include a source of cooling fluid driven by an engine of the aircraft, a source of bleed air driven by the engine and a heat exchanger configured allow the cooling fluid to pass over tubes through which the bleed air flows. The heat exchanger may have a high-temperature zone constructed from material with a first density, and a low-temperature zone constructed from material with a second density lower than the first density.

Abstract: Selected scene regions are imaged. IMAGING CHANNEL: mirrors (preferably MEMS) address an imaging sensor to regions. CALIBRATION CHANNEL: the mirrors direct radiation from a source to a calibration sensor, along an imaging-channel segment. Beam splitter(s) let the channels share optical path at the mirrors. To minimize imaging-channel diffractive blur, the calibration channel modifies wavefront angle and smoothness at the mirrors—measuring (and setting mirrors to optimize) PSF sharpness, then applying these measurements (and settings) to optimize imaging-channel settings by iterative multidimensional gradient search. An afocal lens receives scene radiation, magnifying deflection at the scene. An FOR is imaged on the imaging sensor; the mirrors address the sensor to a narrow FOV within the FOR; the lens enlarges deflections to cover the FOR. Plural diffraction-grating orders communicate between calibration source and sensor when the selected region is in plural scene portions, regardless which FOV is addressed.

Abstract: Selected scene regions are imaged. IMAGING CHANNEL: mirrors (preferably MEMS) address an imaging sensor to regions. CALIBRATION CHANNEL: the mirrors direct radiation from a source to a calibration sensor, along an imaging-channel segment. Beam splitter(s) let the channels share optical path at the mirrors. To minimize imaging-channel diffractive blur, the calibration channel modifies wavefront angle and smoothness at the mirrors—measuring (and setting mirrors to optimize) PSF sharpness, then applying these measurements (and settings) to optimize imaging-channel settings by iterative multidimensional gradient search. An afocal lens receives scene radiation, magnifying deflection at the scene. An FOR is imaged on the imaging sensor; the mirrors address the sensor to a narrow FOV within the FOR; the lens enlarges deflections to cover the FOR. Plural diffraction-grating orders communicate between calibration source and sensor when the selected region is in plural scene portions, regardless which FOV is addressed.

Abstract: Selected scene regions are imaged. IMAGING CHANNEL: mirrors (preferably MEMS) address an imaging sensor to regions. CALIBRATION CHANNEL: the mirrors direct radiation from a source to a calibration sensor, along an imaging-channel segment. Beam splitter(s) let the channels share optical path at the mirrors. To minimize imaging-channel diffractive blur, the calibration channel modifies wavefront angle and smoothness at the mirrors—measuring (and setting mirrors to optimize) PSF sharpness, then applying these measurements (and settings) to optimize imaging-channel settings by iterative multidimensional gradient search. An afocal lens receives scene radiation, magnifying deflection at the scene. An FOR is imaged on the imaging sensor; the mirrors address the sensor to a narrow FOV within the FOR; the lens enlarges deflections to cover the FOR. Plural diffraction-grating orders communicate between calibration source and sensor when the selected region is in plural scene portions, regardless which FOV is addressed.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1-20 wt % more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800-975° C. and over 3 to 15 minutes.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1-20 wt % more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800-975° C. and over 3 to 15 minutes.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1–20 wt % more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800–975° C. and over 3 to 15 minutes.

Abstract: The present invention provides a braze foil comprising titanium and zirconium layers covered by one or more layers of copper, nickel or an alloy of copper and nickel such that neither the zirconium or titanium layers are exposed to the atmosphere. The braze foil may further be layered onto a base material during production to form a braze-clad base material. Methods for brazing a base material with the braze foil are also provided.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1-20 wt % more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800-975° C. and over 3 to 15 minutes.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1-20 wt % more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800-975° C. and over 3 to 15 minutes.

Abstract: A heat exchanger of the plate-fin type has fins of one metal brazed to a plate made of a different metal for use in oil coolers, condensers, evaporators, and the like. The distortion-prone titanium fins of conventional heat exchangers may be replaced with another metal, such as a stainless steel or a nickel based alloy to provide a structure that is resistant to crushing at the brazing temperature. Fluid or air flow resistance (pressure drop) through the heat exchanger may also be improved if the selected fin metal forms better fin shapes and has fewer burrs than conventional titanium fins. The replacement material may also improve the heat transfer performance of the heat exchanger if the selected fin metal has higher thermal conductivity than titanium.

Abstract: A braze material and method of brazing titanium metals. The material may consist of Ti, Ni, Cu Zr, PM and M where PM is a precious metal and M may be Fe, V, Cr, Co, Mo, Nb, Mn, Si, Sn, Al, B, Gd, Ge or combinations thereof, with the (Cu+PM)/Ni ratio around 0.9. Optionally, a second brazing may be performed to rebraze any braze joint that did not braze successfully. The second brazing material has a lower braze temperature than the first and may consist of a mixture of Ti, Ni, Cu, Zr PM and M with from 1-20 wt% more Zr, PM, M or combinations thereof than the first braze. The braze material may be placed on a base material, in a vacuum furnace, and heated to form a braze joint between the braze and base material. The heating step may occur from about 800-975° C. and over 3 to 15 minutes.

Abstract: A method of brazing a Ti-15 Mo-3 Nb-3 Al-0.2 Si base material includes the steps of coating a braze material onto a base material. The braze material comprises substantially only a Ti--Cu--Ni--Zr mixture, with the mixture comprising about 40 wt % Ti. In particular, the braze material may comprise 40Ti-20 Cu-20 Ni-20 Zr. A following step includes heating the braze material and then forming a braze joint between the braze and base materials. The heating step can occur from about 760 to 932.degree. C. and over 15 to 90 minutes.