Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> Abstract The morphology of the Cu surface of a Cu/ZnO/Al 2 O 3 (60:30:10) catalyst, produced by reduction of the copper oxide component of the catalyst either with H 2 or CO, has been probed by measuring the IR spectra of CO adsorbed on these surfaces. Pre-reduction in H 2 produces a Cu surface, which contains the (110) and (211) faces and which is active in CO 2 decomposition. Re-reduction of the CO 2 -oxidised Cu surface in CO results in a twofold increase in the Cu(211) surface. Re-reduction of the CO 2 -oxidised Cu surface in H 2 results in the restoration of the original Cu morphology, i.e. in a decrease in the Cu(211) surface population. Initial reduction of the copper oxide component of the Cu/ZnO/Al 2 O 3 catalyst by CO produces a surface, which is inactive in the decomposition of CO 2 . <s> BIB001 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> This letter presents experimental results on unlubricated friction, which suggests that stick–slip is described by self-organized criticality (SOC). The data, obtained with a pin-on-disc tribometer examines the variation of the friction force as a function of time—or sliding distance. This is the first time that standard tribological equipment has been used to examine the possibility of SOC. The materials were matching pins and discs of aluminium loaded with 250, 500 and 1000 g masses, and matching M50 steel couples loaded with a 1000 g mass. An analysis of the data shows that the probability distribution of slip sizes follows a power law. In addition, the frequency power spectrum follows a 1/fα pattern with α in the range 1.1–1.3. We perform a careful analysis of all the properties, beyond the two just mentioned, which are required to imply the presence of SOC. Our data strongly support the existence of SOC for stick–slip in dry sliding friction. <s> BIB002 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> The present article presents the results of triboengineering tests of polycrystalline diamonds deposited chemically from the gaseous phase together with intermetallides of the Al-Ti system. The conditions are determined when the diamond wears intensively; these conditions appear due to the use of a metallic catalysis precursor as a counterbody. The study results are expected to contributed to the development of techniques for machining of diamonds of industrial dimensions. <s> BIB003 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> The friction coefficient on rake face was calculated through the cutting forces tested in a series of cutting experiments. These experiments were performed for turning two kinds of hardened steel with four types of coating tool by orthogonal experimental method. The curves of the friction coefficient changing with the cutting process and its dependence on the cutting parameters were analyzed in detail. The results show that the friction coefficient on rake face decreases rapidly during the cutting progress and comes to a steady value, which could be an indication of the self-organization when turning hardened steel with coating tool. <s> BIB004 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> Despite the fact that self-organization during friction has received relatively little attention from tribologists so far, it has the potential for the creation of self-healing and self-lubricating materials, which are important for green or environment-friendly tribology. The principles of the thermodynamics of irreversible processes and of the nonlinear theory of dynamical systems are used to investigate the formation of spatial and temporal structures during friction. The transition to the self-organized state with low friction and wear occurs through destabilization of steady-state (stationary) sliding. The criterion for destabilization is formulated and several examples are discussed: the formation of a protective film, microtopography evolution and slip waves. The pattern formation may involve self-organized criticality and reaction-diffusion systems. A special self-healing mechanism may be embedded into the material by coupling the corresponding required forces. The analysis provides the structure-property relationship, which can be applied for the design optimization of composite self-lubricating and self-healing materials for various ecologically friendly applications and green tribology. <s> BIB005 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> The possibility of influencing friction-induced processes and friction parameters through catalytic phenomena is discussed. A catalytic effect is shown using examples of material treatment and friction with the collection of electric current. The friction-induced catalytic effect is described based on nonequilibrium thermodynamics and the theory of self-organization. Addition of a catalyst into rubbing materials can help increase the wear rate of the materials under mechanical treatment or decrease the wear rate of wear-resistant materials by accelerating spontaneous or nonspontaneous physicochemical processes, respectively. <s> BIB006 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> We experimentally investigate the non-equilibrium steady-state distribution of the work done by an external force on a mesoscopic system with many coupled degrees of freedom: a colloidal crystal mechanically driven across a commensurate periodic light field. Since this system mimics the spatiotemporal dynamics of a crystalline surface moving on a corrugated substrate, our results show general properties of the work distribution for atomically flat surfaces undergoing friction. We address the role of several parameters which can influence the shape of the work distribution, e.g. the number of particles used to locally probe the properties of the system and the time interval to measure the work. We find that, when tuning the control parameters to induce particle depinning from the substrate, there is an abrupt change of the shape of the work distribution. While in the completely static and sliding friction regimes the work distribution is Gaussian, non-Gaussian tails show up due to the spatiotemporal heterogeneity of the particle dynamics during the transition between these two regimes. <s> BIB007 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> This article discusses the peculiarities of self-organization behavior and formation of dissipative structures during friction of antifriction alloys for slide bearings against a steel counterbody. It shows that during self-organization, the moment of friction in a tribosystem may be decreasing with the load growth and in the bifurcations of the coefficient of friction with respect to load. Self-organization and the formation of dissipative structures lead to an increase in the seizure load. <s> BIB008 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> The results of tests on the scoring resistance of newly developed aluminum antifriction alloys and antifriction bronze have been presented. It has been shown that the load of scoring for aluminum alloys is significantly higher than for bronze with a maximum content of the soft structural component, i.e., the best antifriction bronze. <s> BIB009 </s> Application of the Self-Organization Phenomenon in the Development of Wear Resistant Materials—A Review <s> Reaction <s> Combined tests are carried out to determine the mechanical characteristics of pilot antifriction alloys based on aluminum and BrO4Ts4S17 commercial bronze; they are also tested in the laboratory tests for run-in ability. The interrelation of the mechanical characteristics of these pilot alloys with their run-in ability is determined. The interrelation of the mechanical characteristics of aluminum-based alloys with their run-in ability is considered for various degrees of alloying with hardening elements and elements that provide the presence of the soft structural constituent. <s> BIB010
Affinity (kJ/mol) −342 BIB007 −269 −271 −477 In  it is shown that the reactions (8) and (9) can serve as the mechanism of self-organization in a sliding electrical contact. Figure 2 shows the dependencies of the intensity of wear of a carbon current collecting material on the density of electric current. The bifurcation point is shown, out of which develops a thermodynamic branch, as well as the branch of dissipative structures. The experimental procedure and tests described in  . Two samples of current collecting material slide on a ring of copper wire of 600 mm diameter. The width of the wire is 6 mm, and the rotational speed of the ring is 200 rotations/min. Between the sample and the wire an electric current is formed. Wear of the current collecting materials was determined by their decrease in weight. Wear of the wire was determined by the change in the diameter of the wire. In  , based on studies of the friction surfaces of sliding electrical contacts specific to different areas of dependence Figure 2 indirectly confirmed the reactions (8) and (9) on the curve "dissipative structures". The main nonspontaneous stage of the reactions BIB004 and (9) is the decompounding of CO 2 which is adsorbed on copper into oxygen and carbon. In  it is emphasized that in the presence of natural graphite the temperature of the start of the decomposition of the CO 2 reaction is reduced. This is why a current collective material based on natural graphite has been manufactured. The dependency of intensity of wear of this material on the density of electric current is shown in Figure 2 , which suggests that before the bifurcation point, the intensity of wear of the current collecting material based on charred coal was approximately 30 times higher than the intensity of wear of the current collecting material based on natural graphite. After the bifurcation point this variance can grow and in the case of the formation of dissipative structures it can decrease sharply. It needs to be understood that hardness of the material based on charred coal is twice as high as the hardness of the material based on natural graphite. Thus it has become possible to significantly reduce the integral wear of the current collecting material by shifting self-organization to the relatively softer conditions of friction. The second option for reducing the intensity of wear is intensification of nonspontaneous processes in dissipative structures. As applied to sliding electric contacts this implies an increase of velocity of the reactions (8) and BIB007 . Increasing the reactions' velocity enables an increase of absolute value at the negative part of the production of entropy and to reduce the overall production of entropy in Equation BIB002 . In order to increase the reactions' velocity it is proposed to use a catalyst BIB006 . This should result in a reduction of the wear intensity. According to   BIB001  the simplest catalyst of the CO 2 decomposition reaction may be iron. The mixture of the current collecting material based on charred coal has been infused with three types of powders: steel powder, iron powder, and coppered iron powder. The experimental procedure and tests were described in  . Figure 3 shows dependencies of wear of the copper counterbody at the current density of 10.7 A/mm, which corresponded to the "dissipative structures" of the curve in Figure 2 . Figure 3 suggests that the coppered iron powder has little influence on the intensity of wear, the steel powder reduces the intensity of wear by about half, while the iron powder reduces the intensity of wear by at least ten-fold. The wear rate of the collector material behaved similarly. Thus, the use of a catalyst for accelerating the processes with negative entropy production leads to a decrease in wear rate. There are tribosystems in which you need to increase the intensity of wear, for example, when machining parts. It was demonstrated BIB003 on a purposeful use of a catalyst accelerating the processes of positive entropy production for the grinding of artificial diamonds was demonstrated. Entropy 2016, 18, 385 9 of 13 entropy in Equation (7). In order to increase the reactions' velocity it is proposed to use a catalyst BIB006 . This should result in a reduction of the wear intensity. According to   BIB001  the simplest catalyst of the CO2 decomposition reaction may be iron. The mixture of the current collecting material based on charred coal has been infused with three types of powders: steel powder, iron powder, and coppered iron powder. The experimental procedure and tests were described in  . Figure 3 shows dependencies of wear of the copper counterbody at the current density of 10.7 A/mm, which corresponded to the "dissipative structures" of the curve in Figure 2 . Figure 3 suggests that the coppered iron powder has little influence on the intensity of wear, the steel powder reduces the intensity of wear by about half, while the iron powder reduces the intensity of wear by at least ten-fold. The wear rate of the collector material behaved similarly. Thus, the use of a catalyst for accelerating the processes with negative entropy production leads to a decrease in wear rate. There are tribosystems in which you need to increase the intensity of wear, for example, when machining parts. It was demonstrated BIB003 on a purposeful use of a catalyst accelerating the processes of positive entropy production for the grinding of artificial diamonds was demonstrated. Increase of complexity of the content of materials under friction in order to increase the probability of self-organization is exemplified by the development of new antifriction aluminum alloys. Conventional antifriction aluminum alloys contain 2-4 alloying elements, for instance, the alloys Al-20% Sn-1% Cu or Al-10% Sn-2% Pb-1% Cu BIB010 . During the development of new antifriction alloys 7-9 alloying elements have been used simultaneously. The chemical compositions of antifriction bronze, the known aluminum alloy AlSn20, and the new antifriction alloy are shown in Table 2 . Increase of complexity of the content of materials under friction in order to increase the probability of self-organization is exemplified by the development of new antifriction aluminum alloys. Conventional antifriction aluminum alloys contain 2-4 alloying elements, for instance, the alloys Al-20% Sn-1% Cu or Al-10% Sn-2% Pb-1% Cu BIB010 . During the development of new antifriction alloys 7-9 alloying elements have been used simultaneously. The chemical compositions of antifriction bronze, the known aluminum alloy AlSn20, and the new antifriction alloy are shown in Table 2 . Tests were carried out according to the procedure described in BIB008 . The tests were conducted on a friction machine in a "shoe-and-roller" design. The oil was kept in a special bath where the lower part of a rotating steel roller was permanently dipped. The shoe was made of aluminium alloys. The corner radius of the working surfaces was 20 mm; the shoe's length was 10 mm. The counter-body was shaped like a roller and manufactured from steel 1045. The rollers were 40 mm in diameter and 10 mm wide. The working surface of the rollers was polished before testing. The rotation speed of the rollers was 500 rpm. The intensity of wear of the alloys and the steel counter-body has been shown in Figures 4 and 5 , respectively. As a result of the complication of alloying, the intensity of wear of the new antifriction alloy has been reduced approximately 1.5 times, while the intensity of wear of the steel counterbody has been reduced approximately six times. Besides, it has been possible to reduce the contents of tin in the aluminum alloy by half. The breaks are marked with abrupt changes in the coefficient of friction on the dependence of the friction coefficient on load of new anti-friction aluminum alloys BIB009 . The best anti-friction alloy has six sections of reduced friction coefficients corresponding to the time of formation of new secondary structures. The ability of multi-component alloy to adapt to changing frictional conditions is related, in our opinion to high probability of loss of thermodynamic stability in accordance with Equation BIB005 . Therefore, multicomponent alloys have a high ability to self-organize. This results in improved tribological properties in comparison with the alloys with less complex alloying. Tests were carried out according to the procedure described in BIB008 . The tests were conducted on a friction machine in a "shoe-and-roller" design. The oil was kept in a special bath where the lower part of a rotating steel roller was permanently dipped. The shoe was made of aluminium alloys. The corner radius of the working surfaces was 20 mm; the shoe's length was 10 mm. The counter-body was shaped like a roller and manufactured from steel 1045. The rollers were 40 mm in diameter and 10 mm wide. The working surface of the rollers was polished before testing. The rotation speed of the rollers was 500 rpm. The intensity of wear of the alloys and the steel counter-body has been shown in Figures 4 and 5 , respectively. As a result of the complication of alloying, the intensity of wear of the new antifriction alloy has been reduced approximately 1.5 times, while the intensity of wear of the steel counterbody has been reduced approximately six times. Besides, it has been possible to reduce the contents of tin in the aluminum alloy by half. The breaks are marked with abrupt changes in the coefficient of friction on the dependence of the friction coefficient on load of new anti-friction aluminum alloys BIB009 . The best anti-friction alloy has six sections of reduced friction coefficients corresponding to the time of formation of new secondary structures. The ability of multi-component alloy to adapt to changing frictional conditions is related, in our opinion to high probability of loss of thermodynamic stability in accordance with Equation BIB005 . Therefore, multicomponent alloys have a high ability to selforganize. This results in improved tribological properties in comparison with the alloys with less complex alloying. 