Properties of polymeric compositions based on epoxy and functional petroleum polymeric resins

We studied cross-linking, water resistance, and impedance characteristics of polymeric compositions based on epoxydiane and maleinized petroleum polymeric resins. It is shown that epoxy and petroleum polymeric components interact at temperatures of 150°C and higher to form cross-linked copolymers. The gel-fraction content of the composition increases with the acid number of the petroleum polymeric component. Small amounts of tertiary amine enhance the efficiency of its cross-linking. The water resistance and protective properties of epoxy-petroleum polymeric compositions improve as the acid number of petroleum polymeric resins increases and the content of the liquid fraction decreases. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 32, No. 6, pp. 37–42, November–December, 1996.     

Influence of Surface-Modified Conducting Fillers on the Properties of Epoxy Coatings

We have developed a new epoxy composition for antistatic coatings on metallic surfaces, filled with technical carbon and talc, which had been surface-modified by paranitroaniline and phosphoric acid. It has been shown that, with the introduction of modified fillers, the content of gel fraction in an epoxy coating increases by 5–6%, its adhesion becomes 2.5–2.7 times higher, and the amount of organic solvents decreases. We have also established that the electric resistance of the coating is more stable in time as compared with the commercial antistatic ground-coat enamel, and the frequency dependence of the resistance is more clearly pronounced after exposure to a chloride-containing medium, which corroborates the better protective properties of antistatic coatings with modified current conductive fillers. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 4, pp. 53–58, July–August, 2005.     

Effect of Carbon-Containing Conducting Fillers on the Properties of Epoxy Coatings

We have established that antistatic coatings based on EP-0010 putty and graphite have low adhesion to metal and breaking strength but are resistant to the action of an operating environment. The use of carbon black as a conducting additive increases 1.5–3 times the strength of free films obtained on the basis of the given epoxy composition as compared with graphite and decreases their mass losses in an operating environment. The adhesion of epoxy coatings based on the EP-0010 composition modified by carbon black is 2–2.5 times as great as that of coatings with a graphite filler. The use of a plasticizer based on epoxidated vegetable oil instead of an inert phthalate plasticizer in a carbon-containing epoxy composition is promising and, in the case of optimal content of the components, enables one to enhance significantly the physicomechanical characteristics of antistatic epoxy coatings and their resistance to the action of the operating environment. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 2, pp. 109–113, March–April, 2005.     

Utilization of a multitonnage wastes in compositions based on modified epoxide oligomers

We study protective coatings based on modified epoxide oligomers with addition of a waste of the “Khimvolokno” and “Azot” plants and on synergists, derivatives of benzamidazole. Waste utilization is shown to provide a 50% economy of deficient epoxide resins. The developed composition of inhibited protective coatings guarantees the enhancement of their anticorrosive activity at the expense of partial inhibition effects (blocking mechanism, in particular). The augmentation of the chemical resistance of steel with inhibited protective coatings to low-cyclic fatigue is related to the plasticization of polymeric metal-chelate films formed on the metal surface. Technological Institute, Chernigiv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 1, pp. 90–94, January–February, 1999.     

Influence of hydrogen on the long-term strength of tire steels

We establish that the time to fracture of specimens made of 8Mn−8Ni−4Cr steel decreases in tap water at high stresses by a factor of 2.5 and, in the course of electrolytic hydrogenation, by a factor of 35–50 as compared with that obtained in tests in twice-distilled water. The use of a hardening surface treatment and protective coatings under the same conditions increases the long-term strength by a factor of 1.5–2. A combined plasma Al+V₂O₅ coating with subsequent soaking with epoxy compound preserves the plastic characteristics of steel and, hence, increases the time to fracture in the best way. The application of plasma nitride (TiN+CrN+NbN) coatings on the thread and mounting surfaces of elements of a rotor shroud unit gives them a high hardness and resistance to dripping and scoring and prevents the penetration of hydrogen-containing media into the base. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 4, pp. 37–42, July–August, 1999.     

Effect of the modes of formation on the protective properties of conversion-polymeric coatings

We study regularities of changes in the total electrode potential, de resistance, and impedance of lowcarbon steel with conversion-polymeric coatings as functions of the temperature and time conditions of their formation and of the time of holding in corrosive media. We establish the relationship between electrochemical corrosion processes in metal covered with conversion-polymeric coatings and the barrier-adhesion mechanism of the protective action of coatings. We establish the following optimal mode of the application of coatings of modified SKD-1s latex: polymerization for 110–130 sec at a temperature of 220–240°C. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. State University of Chemical Engineering, Dnepropetrovsk. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 32, No. 5, pp. 50–54, September–October, 1996.     

Methodical aspects of determining the elasticity of electrical insulating coatings

We have studied the elasticity of 12 different types of polymeric protective coatings. In the course of pure-bending deformation of rectangular plates—specimens, we controlled their dielectric continuity using an electric-spark flaw detector, measured the direct-current resistance, and looked for the appearance of indications of the fracture of the coating surface under a microscope with a ×30 magnification. We have established that highly elastic coatings lose their dielectric continuity under relative strains an order of magnitude lower than those corresponding to the appearance of cracks on the surface. We have concluded that evaluation of the elasticity of coatings by the criterion of loss of their dielectric continuity is the most correct and reliable approach. We also describe the procedure of tests of specimens. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 6, pp. 65–69, November–December, 2005.     

Nanotechnology-associated coatings for aircrafts

Polymeric epoxy-based composites are modified with nanopowders of silicon oxide (∼ 100 nm). By the method of spraying, these composites are applied to specimens of 2024-T3 aluminum alloy preliminary treated with molybdate solutions to get conversion layers. Three types of polymeric coatings are considered: reference, treated by silica, and with additional polyurethane coatings. The aim of modification of polymeric coatings is to absorb and/or block unwanted ions/molecules (Cl⁻, O₂, OH⁻, H₂O, etc.) and improve the protective properties of the films. The tests carried out by the method of electrochemical impedance spectroscopy, in a salt-fog chamber, and by immersion in a 0.5 M NaCl solution reveal high anticorrosion characteristics of the coating. New coatings are promising for the corrosion protection in the aircraft industry. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 3, pp. 103–108, May–June, 2007.     

Specific Features of the Anticorrosive Action of a Mixture of Nontoxic Pigments in an Epoxy Coating on Steel

We investigate capacitance-resistance characteristics of epoxy coatings on low-carbon steel that contain a strontium crown or a mixture of phosphate and calcium-containing pigments in a primer. Tests were carried out in a medium simulating acid atmospheric precipitation. The protective action of chromate-free pigments hinders the diffusion of an acid medium into a polymeric coating and improves its insulating properties. The swelling of free films and the capacitance of coatings with chromate-free pigments are lower than those of epoxy and epoxychromate coatings. We establish the existence of an incubation period in the protective action of pigmented coatings. In both pigmented coatings, an increase in both the active resistance and frequency dependence is observed. The results of impedance tests show that the anticorrosive efficiency of epoxy coatings with a mixture of nontoxic pigments is on a par with the anticorrosive efficiency of epoxychromate coatings.     

煤制油碱性水储罐内表面无溶剂改性环氧防腐蚀涂料涂层的制备及其性能

煤直接液化制油工艺碱性含硫污水储罐内壁的腐蚀特征复杂,内防腐蚀涂层脱落问题是储罐设备安全的隐患,同时也是制约装置长周期运行的瓶颈。以纳米二氧化硅改性环氧树脂、有机硅环氧杂化树脂与双酚A环氧树脂复配,制备无溶剂改性环氧涂料,用于直接液化制油工艺碱性含硫污水储罐内壁的防腐蚀,并在A3钢表面制备无溶剂改性环氧防腐蚀涂层,采用相关标准测试其性能。结果表明:采用纳米二氧化硅改性环氧树脂可以明显改善无溶剂防腐蚀涂料涂层的耐冲击强度、柔韧性以及交联度;硅烷偶联剂与二氧化硅改性环氧涂料使涂层附着力保持时间明显延长;有机硅环氧杂化树脂可以有效改善涂层抗腐蚀介质渗透能力,有机硅环氧杂化树脂与纳米二氧化硅改性环氧树脂则可以极大地减轻涂层表面和涂层本体在腐蚀性介质中的破坏程度,延长防腐蚀涂层使用寿命,满足煤制油工艺中碱性水储罐的防腐蚀要求。     

Corrosion and electrochemical properties of binary cobalt and nickel alloys

The influence of pH of electrolyte on the tungsten content and current efficiency of a Co–W coating is determined. We determine the corrosion rates of Co–W and Ni–Pd alloys by the polarization resistance method and show that the coatings are classified as belonging to highly corrosion-resistant coatings. The catalytic reactivity of coatings in a model reaction of hydrogen release is assessed. Dependences of the corrosion resistance and catalytic reactivity of Co–W and Ni–Pd alloys on the contents of the components are obtained, and their character is justified. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 6, pp. 89–92, November–December, 2008.     

Production of conversion oxide-ceramic coatings on zirconium and titanium alloys

We consider the possibilities of surface hardening of zirconium and titanium alloys with conversion oxide-ceramic coatings. These coatings have been produced by the method of plasma-electrolytic treatment in alkaline solutions. We have established that the plasma temperature in discharge spark channels reaches (6–9) · 10³ K. The thickness of the coatings is 100 to 120 and 30 to 40 μm, and their microhardness is ∼ 800 and ∼ 1000 MPa for zirconium and titanium alloys, respectively. The functional properties of the coatings depend on the synthesis conditions, including the electrolyte composition, the cathode and anode current densities, and also the treatment time. We have evaluated the thickness, microhardness, and wear resistance of the coatings under conditions of dry friction and cavitation as well as their fatigue strength and corrosion resistance. We have established that this treatment provides a high wear and corrosion resistance of the alloys under study with insignificant decrease in their fatigue strength. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 2, pp. 117–124, March–April, 2006.     

Physicochemical properties of tungsten-carbide and zirconium-diboride galvanic coatings on steel

We study the physicochemical and mechanical properties of galvanic coatings based on tungsten carbide and zirconium diboride and obtained as a result of electrolysis of ionic melts on steels. The thickness of the coatings does not exceed 100 μm. The application of these coatings makes the wear resistance of steel specimens 6–9 and 8–9 times higher and their abrasion resistance 7–8 and 8–10 times higher, respectively. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 1, pp. 68–72, January–February, 2007.     

Influence of the mechanism and parameters of hardening of modified novolac phenol-formaldehyde resins on the physicomechanical properties of the composite

We study the influence of concentrations of the components of reactive compositions and the conditions of production and hardening of phenol-formaldehyde resins with the help of epoxy resins in the presence of polyvinylpyrrolidone on the physicomechanical, thermal, adhesion, insulation, and anticorrosion properties of the composites. The positive effect of modifications with polyvinylpyrrolidone and epoxy resin manifests itself within the following ranges of concentrations: 0.5–1 wt.% of polyvinylpyrrolidone and 25–30 wt.% of ED-20 in the presence of 1 wt.% of N, N-dimethylaniline. Thus, the adhesion strength of a glue based on the developed composition becomes four times higher and constitutes 5–6 MPa; the impact strength, static strength in bending, surface hardness, and the specific bulk electric resistance of the specimens hardened at 150–160°C for 25–30 min become 1.5–2.5 times higher and are equal to 5–6J/m², 15–17 MPa, 350–420 MPa, and (5.5–6.5)⋅10¹⁰ Ω⋅m, respectively. The behavior of these characteristics strongly depends on the conditions of hardening. We optimized the composition of modified phenol-formaldehyde resins, which made it possible to produce materials with predicted properties.     

Wear resistance of plasma coatings for a constant work of friction

We analyze the wear resistance of plasma coatings for a constant work of friction. The dependences of the wear resistance of the coatings are obtained for a broad range of loading conditions. It is shown that the minimum sensitivity to loading conditions is exhibited by the molybdenum coatings. It is also established that the wear resistance of the coatings decreases as the amplitude of displacements increases and the cyclic frequency of the tests decreases due to the intensification of fatigue processes on the surfaces. The comparative characteristics of coatings are presented. __________ Translated from Problemy Prochnosti, No. 5, pp. 94–100, September–October, 2007.     

Complex modifiers for the improvement of protective properties of silicon-organic coatings

Using the results of electrochemical and impedance investigations, we have established that the introduction of modified zinc phosphate to the composition of silicon-organic prime coat, commonly applied for the painting of steel main pipelines at the outlet of gas-compressor stations, improves its protective properties and increases the corrosion resistance of the metal. We also have shown that the introduction of a mixture of modified zinc phosphate with fine filler (omiacarb) to the composition of silicon-organic coatings enables one to improve their protective properties. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 5, pp. 85–89, September–October, 2005.     

Compressive mechanical response of a low-density epoxy foam at various strain rates

We experimentally obtained compressive stress–strain response of a low-density epoxy foam at various strain rates. In particular, compressive stress–strain behavior at intermediate strain rates that has not been previously well understood were characterized by using a modified MTS and a split Hopkinson pressure bar (SHPB). Strain rate effects on the modulus of elasticity and cell-collapse stress for this low-density epoxy foam were determined.     

环氧树脂改性水性聚氨酯的合成研究

采用甲苯二异氰酸酯(TDI-80)、聚醚二醇(N220)、二羟甲基丙酸(DMPA)、环氧树脂和丙烯酸羟丙酯(HPA),合成了环氧改性的双键封端水性聚氨酯乳液.乳液由于含有不饱和双键而具有感光性能,故此乳液可用作水性紫外光固化涂料或胶粘剂的预聚物.实验结果表明,随着环氧树脂用量的增大,涂膜的硬度、耐水性、耐溶剂性及力学性能增强,但乳液外观和稳定性变差,故适宜的环氧树脂添加量为4%～8%.通过傅立叶变换红外光谱、粒径分析仪、凝胶渗透色谱(GPC)和透射电镜(TEM)等对乳液进行了表征.粒径分析仪分析显示,加入环氧树脂后,水性聚氨酯(WPU)分散体粒径增大,粒径分布变宽.凝胶渗透色谱分析表明环氧树脂改性水性聚氨酯提高了聚氨酯的分子量.     

Optimization of the procedure of plasma spraying of erosion-resistant coatings according to strength criteria

It is shown that mechanical characteristics of the coatings depend on their technological conditions of their deposition. We propose a procedure of optimization of the technological process and control over this process according to the criteria of strength and specific consumption of materials by analyzing an example of plasma spraying of erosion-resistant coatings. The erosion resistance exhibits the most stable correlation with the cohesive strength of the coatings. The regression equations are used to determine the maximum levels of cohesive strength of the coatings and erosion resistance for the optimal combinations of technological parameters of. Translated from Problemy Prochnosti, No. 6, pp. 136–151, November–December, 2008.     

Bioactive coatings based on nanodiamond-modified epoxy siloxane sols for stone materials

Using a sol-gel process, we have prepared bioactive organic-inorganic hybrid coatings based on epoxy siloxane sols modified with detonation nanodiamond. The microstructure of the coatings was studied by scanning electron microscopy. The coatings were tested—under both laboratory and urban conditions—for bioactivity against the mold fungi most frequently encountered in the air in large cities. The results suggest that such coatings are potentially attractive for protecting historic monuments from biodeterioration.