The neutral salt spray tests specified in ISO 92271) have been extensively used as the most popular and fundamental tests for estimating the corrosivity (corrosion resistance) of metals and its alloys, and organic or inorganic coatings. The Japanese delegate pointed out that the existing ISO 9227 published in 1990 had some problems and proposed its revision to ISO/TC156/WG7 (Corrosion of metals and its alloys / Accelerated corrosion tests). The Japanese proposed subjects were generally agreed upon. The most significant one was the corrosion reference specimen and the procedure for estimating corrosivity in a test chamber using it. In order to find a suitable reference specimen, international round robin tests were carried out on three test methods − neutral salt spray, acetic acid salt spray and copper accelerated acetic acid salt spray − specified in ISO 9227, with the participation of 18 laboratories in 9 countries. The results of the round robin tests showed that a steel reference specimen was satisfactory in use common to the three test methods. An environment-friendly new cleaning method for removal of corrosion products was also recommended. Thus ISO 9227 should be revised based on those results.
The polluting gas corrosion tests with very low gas concentration are extensively used for estimating the corrosiveness of metals and metallic coatings in service, outdoor and indoor, under conditions of air pollution. However, the test condition of temperature and humidity, 25ºC and 75 %rh, specified in ISO 100621) is temperate, as it was recommended on the basis of the climate in Europe. Therefore it could not be appropriate as a test for the application of materials used under severe environments in subtropical countries as well as in Japan. Under such background we tried to carry out comparison tests between the conditions in ISO 10062 and in the Japanese proposal (40ºC and 80 %rh) based on the typical climate in Japan, for the revision of ISO 10062. From test results, it was found that the proposed condition gave satisfactory results as expected. It now should be specified in the revised ISO 10062.
The influence of surfactants on interfacial tension induced between as-deposited nickel and hydrogen bubbles attached to the nickel electrode in the plating solution was investigated. The influence was evaluated in-situ evaluated by measurement of the electrode's buoyancy caused by hydrogen bubbles attached to the nickel electrode during electroplating. The measurement of buoyancy produced by hydrogen bubbles makes it possible to evaluate successively the performance of the surfactants as wetting agents in the plating solution during nickel electroplating. A part of the as-produced hydrogen adsorbed strongly as bubbles on the as-deposited nickel electrode, which resulted in a pitting formation at the edges of the electrode surface. Four kinds of surfactants made the buoyancy by hydrogen bubbles decrease in the following order : sodium n-dodecyl sulfate >> sodium n-decile sulfate ≥ sodium n-octile sulfate ≥ sodium n-hexyl sulfate. Sodium n-dodecyl sulfate allowed the hydrogen bubbles to leave spontaneously from the electrode without any detectable formation of a pitting.
The present study is concerned with the application of UV light irradiation as the pretreatment method of activated carbon adsorption of saccharin from aqueous solution. For the purpose of improving the efficiency of saccharin removal from water, UV light irradiation was followed by subsequent activated carbon adsorption. Then, the results of saccharin removal between the two cases : activated carbon adsorption combined with UV light irradiation pretreatment and activated carbon adsorption alone, were compared. As the result, it was found that the removal ratio of 43 % at equilibrium state of activated carbon adsorption was increased to 67 % when saccharin solution was pretreated by UV light irradiation for 30 min in the air. The removal ratio of saccharin was kept at 87 % by UV light irradiation only for 180 min in the air, when activated carbon adsorption was not employed. But, the removal ratio of saccharin became almost 100 %, when activated carbon was employed after pretreatment of UV light irradiation of 180 min. Further, the TOC removal ratio obtained only by UV light irradiation of saccharin solution was 26 % after 180 min UV light irradiation in the air. However, the TOC removal ratio after 16 h activated carbon adsorption of saccharin solution was increased to 73 % when saccharin solution was pretreated with UV light irradiation for 180 min in the air.
The effects of surface roughness on the friction characteristics of FC250 cast iron coated with manganese phosphate was examined by using a ring-on-disk test machine. A rotating test piece and a stationary one were used under test conditions, with only the rotating piece coated. The test piece surfaces either had a roughness (Rz) of 0.8, 3.2 or 6.3μm, and the contact pressure at which the pieces were pressed to each other was gradually increased from 1MPa to 9MPa. A manganese phosphate coating is easily worn out, and then a part of the base material is exposed. This makes the surface's friction stable. It was shown clearly that the frictional force strongly depends on the load as well as on the base material's surface roughness. The friction coefficient was as high as 0.04-0.05 when both pieces had the same roughness, but was as low as 0.007 when the pieces had different roughnesses.