ION NITRIDING
A SIMPLIFIED EXPLANATION
Ion
Nitriding is a method of surface hardening iron-based metals. It has
several major advantages over the conventional methods of induction
hardening, gas carburizing and gas salt-bath nitriding. The problems
caused by these processes include distortion, loss of conditioning,
surface crack and scaling. All require some machining after hardening.
Nickel and chrome plating, also used for surface hardening, have the
problems of porosity and flaking, which increase corrosion rates.
HISTORY
Ion
Nitriding, which should not be confused with either conventional gas or
salt bath nitriding, is a low temperature, plasma process which has
consistently proven itself to be a safe, simple, and inexpensive method
for significantly extending the wear life and service life of all types
of precision metal parts and forming dies: including Extrusion Dies,
Stamping & Blanking Dies, Forging Dies, Rolling Dies, and Plastic
Injection Molding Equipment . . . some by as much as eight times their
original life!
Similar
results have also been obtained by Ion Nitriding such precision metal
parts as Gears. Valves Stems, Bearings & Bearing Races, Shafts, Gun
Barrels, Extruder Screws, Fan Blades, Refiner Plates, Crankshafts,
Plungers, Ball Studs, Broaches, Rollers, Wear Plates, Pump Shafts, and
all types of Cutting Blades, as well as a great many other parts whose
service life is often shortened by either galling or sliding abrasive
wear problems.
Ion
Nitriding is a proven nitriding surface hardening process for Stainless
Steels, Alloy Steels, Tool Steels, Carbon Steels, and Cast Iron. It was
commercially developed by the Klockner-Ionon Company in West Germany
during the late 1960's aas an alternative to the more comventional
nitriding, carburizing, and carbonitriding processes. Unlike all other
nitriding processes. Ion Nitriding is not carried out in a furnance.
Rather, it utilizes the principle of a current carrying substance
between an anode and a cathode.
The
Ion Nitriding Process is carried out in a vessel under a minimum vacuum
with the workpiece serving as the cathode and the vessel wall acting as
the anode. Application of high voltage DC power causes the nitrogen to
ionize and glow around the surfaces of the workpiece. The nitrogen ions
bombard, penetrate, and harden all exposed surfaces of the workpiece.
The operating work temperature during the Ion Nitriding Process is
produced strictly by the kinetic energy from this ion bombardment
process.
Controlling
the Ion Nitriding Process variables of current density, temperature,
gas atmosphere, and gas pressure allows the structure, thickness,
hardness, and homogeneity of the Ion Nitrided surface layers to be
independently and precisely controlled. The result is a workpiece
surface with excellent gliding abrasion resistance, fatigue strength,
hardness, and corrosion resistance.
