V. G. Lapteva

Effect of composition and structure of nitrided iron alloys on wear resistance under friction and sliding

Characteristic features of the formation of the wear-resistant structure of the nitrided model alloys with body-centered cubic (bcc) and face-centered cubic (fcc) lattices are studied, including Fe-Mo, Fe-Cr, Fe-Al, Fe-Ni-Cr, Fe-Ni-Al, Fe-Ni-Ti, and Fe-Ni-Cr-Al-Ti. Interrelations are established between the parameters of the structure of the nitrided layer and the wear resistance of alloys. It is shown that, in alloys with the bcc lattice, maximum wear resistance is achieved by the formation of incoherent particles of nitrides of alloying elements, and the maximum hardness can be found in the alloy with coherent nitrides. In alloys with the fcc lattice, maximum hardening during nitriding and wear resistance are achieved at the stage preceding the rupture of coherent communication of the nitride with the lattice. Interconnections of characteristics of the structure of the nitrided layer and the wear resistance are discussed in the context of the formation of the wear-resistant structural state of alloys.

Application of the microplasma method for strengthening of the near-surface layer of samples made from steel 45

Strong local interaction of microplasma discharges with samples made from construction steel 45 is investigated experimentally. It is found that a remelted region with strongly changed physicochemical properties of the material is formed in the near-surface layer of samples treated with microplasma discharges. It is shown that roughness, microhardness, wear resistance, and other properties of treated samples made from steel 45 differ considerably from the corresponding starting values.

Analysis of microplastic deformation processes of surface layers of nitrided structural steels

A model of microplastic deformation in surface layers of nitrided structural steels under the incoherent boundaries of nanodisperse reinforcing particles formed upon thermochemical treatment is considered, allowing the adaptive evolution of deformation without the accumulation of defects at the near-boundary zones, which provides high wear resistance of the material.

Mechanical Properties of Surface Layers of Structural Steels After Nitriding and Possibilities of Adaptation of Their Nanostructure to Contact Deformation

The mechanism of plasticity of surface layers of structural steels after nitriding that yields nanosize particles with incoherent boundaries is considered with allowance for the possibility of adaptation diffusion processes initiated by friction strain.

Strengthening surface layers of samples made of steel 45 using microplasma treatment

The results of experimental studies of the strong local interaction of microplasma discharges with samples made of steel 45 are presented. On the surface layer of the samples, a remelted area with altered microgeometrical, mechanical, and tribological properties of the material is formed.

Physical fundamentals of criterial estimation of nitriding technology for parts of friction units

Characteristics of the structure and properties of surface layers of nitrided structural steels and alloys, which affect the level of surface fracture under friction, are studied. A generalized structural parameter for optimizing the nitriding process and a rapid method for estimating the quality of the surface layer of nitrided parts of friction units are developed.

Strain hardening and wear resistance of nitrated steels and alloys

This study considers the results of an experimental evaluation of the ability of superficial layers of nitrated steels and alloys to resist damage in the conditions of frictional deformation and superficial plastic deformation. A new approach is offered to evaluate and choose modes of nitration of parts of friction assemblies.

Effect of nitriding on wear resistance of iron alloys with various lattice types

The paper considers the characteristics of the formation of the wear-resistant structure of nitrided model alloys with bcc and fcc lattices: Fe-Mo, Fe-Cr, Fe-Al, Fe-Ni-Cr, Fe-Ni-Al, Fe-Ni-Ti, and Fe-Ni-Cr-Al-Ti. The relationships between the structure characteristics of the nitrided layer and the wear resistance of the alloys are found. The maximal wear resistance of the alloys with the bcc lattice of the matrix is shown to be attained when incoherent particles of nitrides of the alloying elements appear; the maximal hardness corresponds to the alloy that contains coherent nitrides. In the alloys with the fcc lattice, the maximal hardening under nitriding and the maximal wear resistance are achieved at the stage that precedes the rupture of the coherent bond between the nitride and the matrix. The relationships between the structure characteristics of the nitrided layer and the wear resistance are discussed from the viewpoint of the formation of a wear-resistant structure state of the alloys.

A new method of formation of a durable microrelief on the surface of samples made of cobalt-chromium alloy

Experimental studies of strong local interaction between microplasma discharges and samples made of cobalt—chromium alloy were performed. It was established that, in the near-surface layer of samples treated with microplasma discharges, a remelted area with greatly changed physicochemical properties is formed. After microplasma treatment, the surface of samples becomes considerably rougher, which improves surface cohesion (adhesion) with various materials (ceramics, plastics, etc.) when durable composite structures are formed.

The Effect of Microplasma Treatment on the Properties of a Near-Surface Layer in Specimens of a Ni-Cr Alloy

A strongly localized interaction of microplasma discharges with samples of a nickel-chrome (Ni-Cr) alloy is experimentally studied. In a near-surface layer of the specimens, a remelted area is created, which is characterized by strongly modified physicochemical properties of the material. This modification of the near-surface layer of Ni-Cr samples significantly improves their adhesion with different materials (ceramics, plastics, etc.) when durable composite structures are created.