Multi-component boron coatings on low carbon steel AISI 1018

CHAPTER 2
BORONIZING
2.1 Objective
Boronizing is a thermo-chemical surface hardening process by which <strong>boron</strong> atoms diffuse
into a base metal (steel) and form a hard metallic boride layer on the surface. The
<strong>boron</strong>izing process can be applied to both ferrous and nonferrous materials by heating the
materials at the temperature range of 700 to 1000°C (equivalently 1300 - 1830°F) for
several hours. The process results in the metallic boride layer of about 20-300 pm thick.
2.2 Overview of Boronizing
Boronizing is a thermo-chemical surface hardening process by which <strong>boron</strong> atoms diffuse
into a base metal (steel) and form a hard metallic boride layer on the surface. The
<strong>boron</strong>izing process can be applied to both ferrous and nonferrous materials by heating the
substrates at the temperature range of 700 to 1000°C (equivalently 1300 to 1830°F) for
several hours. The process results in forming the metallic boride layer of about 20-300
pm thick, which yields the outstanding properties of high hardness, good wear and
corrosion resistances, and moderate oxidation resistance at high temperatures. Unlike
most metals and alloys, aluminium and magnesium alloys have not been successfully
<strong>boron</strong>ized by existing techniques because their melting temperatures are very low. In
addition, copper alloy is unable to form the stable boride phase [4].
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