Versailles Project on Advanced Materials and Standards (VAMAS project) was set up in 1982. Since then, 22 Technical Working Areas have been established, one of which was Surface Chemical Analysis, In the VAMAS project, the accuracy of quantitative analysis by Auger Electron Spectroscopy or X-ray Photoelectron Spectroscopy was examined by Inter-Laboratory Study, and the “standard” procedures for the quantitative analysis have been proposed. These proposed procedures were passed to ISO, and some of these have been ISO standards after the discussions in TC 201. In this paper, the activities of VAMAS and ISO are introduced, and the proposed calibration procedures for the energy and intensity scales of the electron spectroscopy are explained. The software to share spectra with ISO format is also briefly explained.
Alloying and impurity elements are more or less segregated at surface and grain boundaries of metals and alloys. Surface analytical techniques have been applied to characterize the segregation behavior, and provided characteristic features of each element. The present paper reviews some typical results of the segregation or enrichment behavior of the elements in polycrystalline alloys, especially steels, and discusses the effect of the microstructure on the surface and grain boundary segregation.
Modern techniques of analytical and structural investigation have been providing an increasing amount of detailed information about precipitation, distribution and state of the microalloying element in metallic materials and contribution to the understanding of their various roles and effect. This paper reviews the contribution of chemical and instrumental analysis to the characterization of metallic materials. This methods include advanced techniques of precipitates analysis, local probe analysis, structural analysis, and direct or in situ observation.
The structure and unique feature of a scanning atom probe (SAP) are described. The atomic level mass analysis by the SAP is demonstrated by analyzing the diamonds formed by the chemical vapor deposition (CVD), graphites, vitreous carbon and silicon microtips fabricated by lithographic process. The analysis revealed that the CVD diamonds contain a large amount of hydrogen. Furthermore, a significant difference between the mass spectra of the diamonds, graphite and vitreous carbon is noticed. The study also shed light on the oxygen, carbon and fluorine diffusion into the silicon tips immersed in hydrofluoric acid. Applicability of the SAP for the study of corrosion process is discussed.
Copper tubes have been widely used for water supply and heat exchangers. In such systems copper tubes often suffer from type I pitting-corrosion. A mechanism of the type I pitting-corrosion on copper tubing has been presented, but a initiation mechanism of the pitting corrosion is still unknown. In this paper we aimed to clarify the initiation mechanism of the pitting corrosion. Copper-tube specimens were immersed in a circulating solution. The solution had been used for heat exchangers at a Japanese factory where the water leakage occurred by the pitting corrosion on copper tubes. The solution contained tiny precipitates resulted from corrosion of galvanized steel pipe. During the immersion test changes in the surface state of a copper tube was analyzed by in situ RAMAN (in situ Raman Spectroscopy), SEM (Scanning Electron Microscope), EPMA (Electron Probe Microanalysis), AES (Auger, Electron Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy). The pitting corrosion was observed only in the test solution which had been used for heat exchangers. It was considered that Cu2O film on the copper-tube surface became less stable on which the tiny precipitates deposited, and that Cu2O film could not protect the copper-tube surface. It will be the cause why the type I pitting-corrosion occurred.
The temperature influences on the corrosion rate of hot-dipped aluminized steel in the seawater were investigated for the galvanic couples of the aluminum/carbon steel, the aluminum/Fe-Al alloy, the aluminum/stainless steel, the Fe-Al alloy/carbon steel, the Fe-Al alloy/stainless steel, and the carbon steel/stainless steel. In all the couples, the corrosion rate of aluminum is larger than the corrosion rate of aluminum which is not connected with other metals. The corrosion rates grow in order of aluminum/carbon steel>aluminum/stainless steel>aluminum/Fe-Al alloy. The corrosion rate of aluminum connected with the carbon steel is the largest. The corrosion rate is seven times larger than the corrosion rate of aluminum, which is not connected with other metals. The galvanic corrosion rate of the carbon steel, which is connected with Fe-Al alloy or stainless steel, is larger than the corrosion rate of aluminum, which is not connected with other metals. The galvanic corrosion rate of the carbon steel is 1.3-1.8 times larger than the corrosion rate of carbon steel which is not connected with other metals.
To manufacture a highly reliable CFC (Chlorofluoro Carbon) decomposition device, we desire to reduce various possible potentials in the device. This device has the advantage in operating at lower temperature utilizing catalysis for the decomposition. In this device, three parts have high corrosion potentials. These three are (1) a radiator (2) a dehydrator and (3) a fan. As a result of taking possible effective measures to these parts, it became possible to produce a decomposition device with less corrosion problems.
Diamond-like carbon (DLC) films were coated on SUS 304 stainless steel using an ionization deposition method and the area of defects in the films was determined by the critical passivation current density (CPCD) method. The area of pinhole defects in the DLC films (Ri) was evaluated as functions of applied negative bias voltage and the film thickness. The value of Ri for the films thinner than 100nm was not influenced by the bias voltage. On the other hand, the value of Ri for the films thicker than 100nm decreased with increasing bias voltage. For each bias voltage, the density and size of the defects in the DLC films decreased with increasing their thickness. In particular, the Ri-value of the film of 550nm thickness prepared at the bias voltage of -2000V was approximately 0.01%, being lower by a factor of 100 than that of TiN films with similar thickness which was prepared by hollow cathode discharge technique. Therefore, it is concluded from the present work that the protection ability has been improved remarkably by the DLC films (below 600nm) prepared by the ionization deposition method.