THE INFLUENCE OF MICROSTRUCTURE AND HYDROGEN-CONTAINING ENVIRONMENT ON THE INTENSITY OF CAST IRON AND STEEL DAMAGE BY SLIDING FRICTION
PART 1. THE CONSTRUCTION OF A GENERALIZED MODEL OF SURFACE LAYER FRICTION OF GRAPHITIZED STEEL AND CAST-IRON OBJECTS
PART 2
PART 1, PART 2, PART 3, PART 4, PART 5, PART 6, PART 7
RIS 1
a) b) c)
Fig. 1. Schemes of a structure of superficial and near layers:
a) According to Lavrovsky [8]: 1 - adsorbed components; 2 – adsorbed gases; 3 - oxides and non-destroyed material; 4 - initial structure.
b) According to Bernard (after abrasive deterioration): [9]: 1 – non-destroyed base; 2 - transitive zone; 3 - zone of the focused crystals; 4 - zone of non-directional crystals .
c) According to Kostetsky [10]: 1 - secondary structures of the second type; 2 - secondary structures the first of type; 3 – above surface layer; 4 - initial structure.
Among the most developing methods are nanotechnologies. Layered hydrogen intercalated nanoparticles can be used both in manufactured objects and in lubricants (MoS2, C, CaSe, InSe etc.).
However, the scheme presented above does not reflect some features of cast-iron microstructure. In Fig. 4 the pictures of graphitized cast-iron microstructures are presented. As a rule, the role of structural and phase components during various frictions can be seen differently; and depending on a specific quantitative ratio the components (morphology, particles distribution, sizes, etc.), the intensity of cast-iron wear will be different [16].
For instance, the influence of graphite can be dual. On the one hand, it reduces the contact interaction (excludes seizure) between rubbing surfaces during dry friction [17, 18]. On the other hand, by separating the metal matrix, it reduces the durability of material. Some facts do not allow us to explain the lubricating ability of graphite only by means of the layered structure [19]. The friction force in lubricating graphite is higher in dry air than in damp air. The friction force in an atmosphere of nitrogen is much stronger than in air or in hydrogen, and in dry nitrogen it is higher than in damp nitrogen. It is necessary to have moisture films of oxides to utilize the lubricating abilities of graphite. Humidity and оxide films on metal surfaces, produced by moisture, improve the adhesion of graphite to the surface.
Fig. 3. Microstructure of the deformed retaining ring manganese steel
Fig. 4. Microstructure of graphitized cast-iron × 100.
PART 1, PART 3, PART 4
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