| 摘要 |
<p>The invention provides a boiling surface for heat exchangers comprising on a metal base a metal layer applied thereto, in which the layer comprises individual partly- cohering metal particles of various shapes, the layer is substantially free from continuous capillaries and closed pores, and the depth of the voids left between individual metal particles and open towards the boiling surface is on average more than 40% of the thickness of the layer and the thickness of the layer is from 30 to 300 mu m as measured over the highest protuberance. The invention also provides a process for the preparation of such a metal layer in which the particles are applied to the metal base by means of a powder flame spray technique in which the metal particles are injected into a gas flow heated by combustion of two gases and cooled and accelerated by means of a cooling gas, the mass balance of all the component flows responsible for such gas flow having a stoichiometric ratio of combustible gas and oxygen. <IMAGE></p> |
