Abstract: A heat exchanger/evaporator for transferring heat from a first heat exchange fluid to a liquid to be evaporated into a gaseous second heat exchange fluid that includes a thermally conductive element 30 separating a first flow path 34 for the first heat exchange fluid and a second flow path 36 for the second heat exchange fluid. A first surface is on the element 30 in heat exchange relation with the first flow path 34 and a second surface is on the element 30 opposite the first surface and is in heat exchange relation with the second flow path 36. A hydrophilic coating 50 is bonded on part of the second surface and includes a powder of nominally spherically shaped particles including nickel, chromium, aluminum, cobalt and yttrium oxide bonded together with a braze metal predominantly made up of nickel, chromium and silicon and diffused into the nominally spherically shaped particles and the second surface.

Abstract: Potential difficulties in surface modification of a substrate are avoided by using a mixture that includes a ceramic powder, a brazing material and a flux. Exposure to an elevated temperature activates the flux and at least partially melts the brazing material. Upon cooling, the melt solidifies to bond the ceramic powder to the substrate surface an create the modification.