This paper reviews some main development and the application of rare earths in the fields of
thermo-chemical treatment and
some surface engineering technology, introduces the effect of RE on the technical process and the surface modification in
carburizing, boronizing, ion implantation and plasma plating combining with author's results The experiments show that the process of carbulizing and boronizing for steel are accelerated obviously under the action of activity and catalysis of RE, the permeating rate is increased by a factor of 20~30% compared with conventional carburizing and boronizing Carburizing and boronizing layer with excellent qualities are obtained with a good resisting abrasion and toughness The microhardness and wear-resistant of steel surface have been obviously improved through implanting RE It is also found that addition of suitable amount of RE in Ti-N coating can obviously enhance binding force between the coating and substrate The alloying effect of RE on the surface modification layer is analyzed and discussed