Abstract: In subjecting a steel workpiece to nitriding by glow discharge, formation of brittle nitrogen compound is restrained and the surface hardened layer with a nitrogen diffusion layer of high toughness is obtained by making the gas atmospheric condition the gas mixing ratio of N.sub.2 :H.sub.2 =1:2-40. By mixing Ar gas in the above gas atmospheric condition additionally, glow width is adjusted and glow discharge is allowed to enter into narrow concaves at the surface of a workpiece.
Abstract: A device is disclosed for detachably coupling a wheeled oxygen tank cart to a wheelchair such that they are transportable together as a unit without the need of a separate operator of the cart. The device is adjustable in length such that various sizes of wheelchairs may be accommodated. In one embodiment, the oxygen cart rolls in tandem with the wheelchair during use of the device; in another embodiment, the oxygen cart is wholly supported on the wheelchair by the device.