GAS CYLINDER FOR THE STORAGE AND DELIVERY OF P-TYPE DOPANT GASES

摘要

A corrosion resistant gas cylinder includes an electroless nickel-boron layer overlying the inner surface of a steel alloy cylinder. The nickel-boron layer has a thickness of at least about 20 micrometers and a porosity of no greater than about 0.1%. The electroless nickel-boron layer has a boron content of at least about 1% by weight and a surface roughness of no greater than about 5 micrometers. Prior to introducing liquefied gas into the gas cylinder, a cleaning process is carried out using a two-step baking process to clean the surface of the nickel-boron layer. The nickel-boron layer substantially reduces the contamination of liquefied corrosive gases stored in the gas cylinder by metal from the steel wall surface underlying the nickel-boron layer. Metal contamination levels of less than about 55 ppb of iron, 10 ppb of chromium, and 5 ppb of nickel by weight can be maintained in liquefied corrosive gases stored for an extended period of time in the electroless nickel-boron plated gas cylinder.

主权项

1. A high-pressure steel gas cylinder for the containment of P-type dopant gases comprising:
a cylinder wall having an inner surface; and an electroless nickel-boron layer overlying said inner surface wherein said electroless nickel-boron layer has a thickness of at least about 20 micrometers, a porosity of no greater than about 0.1%, and a surface roughness of no greater than about 10 micrometers wherein the electroless nickel-boron layer is subjected to an acid wash and a hot deionized water wash, followed by a first bake under continuous nitrogen flow and a second bake under vacuum pressure wherein high-pressure gas cylinder is charged with a P-type dopant gases.