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1.
The corrosion properties of TiCN, TiCN – AlN, and (TiCN – AlN) – (Fe – Cr) ceramics as well as those of the individual components TiN and TiC in a 3% NaCl solution have been investigated. The kinetics and the mechanism of anode dissolution of metals and oxidation of specimens have been studied by using polarization curves, chemical and x-ray phase analyses, Auger electron spectroscopy, and scanning electron microscopy (SEM). TiCN and TiCN – AlN composites have been found to be the most corrosion-resistant. The presence of a metallic binder in the titanium carbon nitride somewhat decreases the corrosion resistance of the ceramics. On the whole, however, the ceramics developed boast a significantly higher corrosion resistance than that of structural steel.  相似文献   
2.
Use has been made of potentiodynamic polarization curves, XRD, and scanning electron microscopy (SEM) in the electrolytic oxidation in 3% NaCl solution for specimens of nitrogen-deficient zirconium nitride (ZrN0.67, ZrN0.77, ZrN0.87, and ZrN0.97), as well as pure zirconium. In all cases, the anodic polarization curves have several stages which characterize during oxidation both active dissolution of ZrN x and Zr in the electrolyte as well as the formation of surface layers of ZrOCl2, ZrN x O y , and α‐ZrO2 of monoclinic form. The corrosion resistance of single-phase ZrN x specimens in 3% NaCl solution decreases in the sequence ZrN0.97 → ZrN0.87 → ZrN0.77, and the initial stages of interaction between the specimen surface and the electrolyte largely determine the subsequent behavior of specimens. It is found that ZrN x containing a large number of nitrogen atom vacancies, in particular ZrN0.77, is closer in corrosion behavior to metallic zirconium than it is to stoichiometric ZrN (the reduction in the corrosion resistance is undoubtedly due to the reduction in the ionic-covalent components of the bonds in ZrN x ).  相似文献   
3.
The kinetics of titanium carbide oxidation in oxygen over the temperature range of 600–1200°C and oxygen pressure from 0.1 to 740 Torr have been studied with a vacuum microbalance. Layer-by-layer x-ray analysis, petrography, metallography, and gas chromatography have been used to analyze the oxidation products. A paralinear nature of the oxidation of material was established, and the rate constants of the process were calculated for the corresponding parabolic and linear portions of the kinetic curves. It was shown that a gaseous product, CO2, formed, as well as a solid product, TiO2 (rutile), both stoichiometric and nonstoichiometric. The lower oxides, Ti3O5, Ti2O3, TiO, were noted in the scale at temperatures from 700 to 800° and low oxygen pressures, their relative quantity rising with decreasing pressure. Based on x-ray analysis and microhardness measurements, it was concluded that titanium oxicarbides formed in the TiC, directly adjacent to the scale. A possible oxidation mechanism of titanium carbide is proposed.  相似文献   
4.
The oxidation kinetics and structure of the oxide scales formed on high-density SiC were studied in molecular oxygen at 740 Torr and in a glow-discharge oxygen plasma at 0.1 Torr at temperatures of 1000, 1100, and 1200°C. The monatomic oxygen formed by the glow discharge markedly increased the reaction rate and the vaporization of some of the oxidation products. The marked differences in kinetics suggest that the rate-controlling step during oxidation in molecular oxygen is the dissociation of adsorbed diatomic oxygen to the monatomic species. Films formed in molecular oxygen were mostly amorphous SiO2 with small inclusions of SiC and graphite, whereas films formed in dissociated oxygen were primarily amorphous SiO2 containing SiO, S2O3, and the coesite form of SiO2.  相似文献   
5.
A new aluminum protective ATsKM alloy was developed in the Institute for Problems in Materials Science of the Ukrainian Academy of Sciences on the basis of industrial wastes and scrap of AMg alloys. Electrochemical polarization investigations demonstrate that the dissolution of this alloy is uniform and not accompanied by passivation both in a 3% NaCl solution and in a medium of saline soil. In addition, its stationary potential is rather high (–1.11 V in the first case and –1.07V in the second case). In the course of field tests on the body of the Fedor Erozidi ship in the Baltic Sea and Pacific Ocean, it was shown that the protective potential of ATsKM alloy is by 100 mV more negative than the potential of conventional AP3 alloy. Extensive implementation of ATsKM protectors (whose performance is proved to be quite high) produced according to new native technologies would make it possible to reduce or even eliminate our dependence on imported protectors and save costs spent for the electrochemical protection of metal structures against corrosion under operating conditions.Frantsevich Institute for Problems in Materials Science, Ukrainian Academy of Sciences, Kiev. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 3, pp. 7–13, May–June, 1995.  相似文献   
6.
We have used thermogravimetry to study the kinetics of high-temperature (up to 800 °C) oxidation of the alloy 58.3 mass% Au - 41.7 mass% Cu with isothermal heating of the specimens. Using petrographic analysis of the oxide layers, we determined the reaction products. We have shown that up to 200 °C, the indicated alloy is not oxidized at all. More rapid oxidation of the alloy is observed at temperatures above 400 °C. Up to 500 °C, an inner layer consisting of Cu2O predominates in the two-layer scale on the alloy, while the outer CuO layer has a significantly smaller thickness. At 600 °C, the upper layer of scale contains Cu2O while the lower layer contains Cu2O and gold. At higher temperatures, all the way up to 800 °C, the scale is two-layer as before but its upper layer contains CuO while its lower layer contains Cu2O and small gold rods distributed in that oxide. Thus we have established three oxidation regions characterized by different scale phase compositions and different mechanisms for the process, mainly due to transition from an ordered state of the alloy (intermetallic AuCu3) to a completely disordered solid solution of gold in copper. We used the Arrhenius equation to calculate the apparent activation energy for oxidation: E1 = 20.4 kJ/mole for the temperature range 400–500 °C and E2 = 9.5 kJ/mole for 600–800 °C. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 85–91, July–August, 2005.  相似文献   
7.
We studied the electrochemical properties of a sacrificial-anode alloy based on aluminum and magnesium, into which calcium, along with zinc, was introduced as an antipassivator. For the production of this alloy, we used waste and scrap of aluminum-magnesium alloys. In addition to iron and silicon admixtures, it contains a significant amount of copper. Aluminum-based solid solution is the main phase of the new sacrificial-anode alloy, and its second phase represents Cax Zny Alz intermetallic compound, which is distributed uniformly over the volume. The proposed alloy was used for the corrosion protection of seagoing ships of the Baltic Steamship Line. It was also tested successfully in waters of the Pacific and in corrosive brackish soils of Southern Ukraine and Middle Asia. These sacrificial anodes have an efficiency of ∼85% and a stationary potential in seawater of −1.10 v relative to a copper-sulfate reference electrode.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 5, pp. 95–98, September–October, 2004.  相似文献   
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The corrosion resistance of titanium-chromium-diboride-based ceramic materials and cermets in 3% NaCl solution (to simulate sea water) is studied by the method of potentiodynamic polarization curves. The composition and microstructure of oxidized specimen surfaces are examined. Adding small amounts of AlN (5 to 10 vol %) to TiCrB2 provides an essential improvement of the corrosion resistance. Introduction of an NiAlCr metallic binder into the material composition results in a lower resistance to anodic oxidation.  相似文献   
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