Microstructures of a powder metallurgy-hot-isostatically pressed super duplex stainless steel forming in industrial heat treatments

The microstructures of a powder metallurgy/hot-isostatically pressed super duplex stainless steel, designed and manufactured for massive components of paper machines, were studied after heat treatments simulating the industrial production. It was shown that copper precipitates in the ferrite phase as ɛ phase. Morphologically, the copper precipitates are of two types—nearly spherical particles of typical size from 30 to 50 nm, and rodlike particles 30- to 35-nm wide, and up to 700-nm long. The main observations on copper precipitation in modern super duplex stainless steels are similar to those in low-alloy steels. Copper particles were shown to be the nucleation sites for the formation of secondary austenite and to pin the boundaries of sigma phase.     

Abrasive wear of steel against gravel with different rock–steel combinations

Wear testing equipment and tests used in research laboratories are often miniature or simplified versions of real applications. For example standardized ASTM dry sand rubber wheel abrasion test G 65 and pin abrasion test G 132 are widely used to study materials’ abrasion wear resistance. The test results, however, do not always correlate too well with the results obtained from real wear conditions. One reason for this is, for example, that in the crushing applications of mining industry the abrasive size is usually much larger than that used in the laboratory wear tests. To study the abrasive wear caused by larger size gravel, new three-body abrasion test equipment was therefore constructed. The equipment uses the pin-on-disk principle with free abrasive particles of sizes up to 10 mm. During the test the pin is repeatedly pressed against a fixed amount of abrasive that is rotating with the disk having confining walls. As the pin is prevented from touching the counterbody, only the abrasive acts as the wearing agent.Three steels of different hardnesses were cross-tested as pin–disk pairs and as pins against a rubber disk using three igneous rock gravels with different crushability properties as abrasives. The wear was measured as mass loss from both the pin and the disk, and the rock comminution was measured by sieving. The results indicate that the mechanism of wear is greatly affected by the hardness of the counterbody. When using large size abrasives, the rate of comminution is also a very important factor that can significantly affect the wear test results.     

Trends of energy efficiency in Finnish road freight transport 1995–2009 and forecast to 2016

A framework for modeling and analyzing the energy efficiency of road freight transport is presented in this paper. This framework is tested by using the data from the Finnish Goods Transport by Road statistics. The data was enhanced by calculating the fuel consumption for each trip in the data. To calculate this, weight-fuel consumption functions were estimated for each Euro-class vehicles and road type. This is a new method for analyzing the energy efficiency of road freight transport and it could be applied also in other countries gathering freight transport data with continuous company surveys. The analysis show that the energy efficiency of road freight transport in Finland improved during 1995–2002, but has declined since. The major drivers in the development have been the changes in the level of empty running and vehicle fuel efficiency. Extrapolating current statistical trends of factors that influence the energy efficiency show that the target set by the Finnish government for improving energy efficiency by 9% until 2016 will not be achieved. However, the target is possible to be achieved by a combination of small changes to some determinants.     

Use of nanoparticular and soluble anionic celluloses in coagulation-flocculation treatment of kaolin suspension

In this work, the effectiveness of a novel, combined coagulation-flocculation treatment based on alum and soluble or nanoparticular anionic derivatives of dialdehyde cellulose, ADAC, was evaluated by studying the removal of colloidal material in a model suspension containing kaolin. Four different ADACs with varying degrees of substitution, size and water solubility were synthesized by periodate oxidation and sulfonation of cellulose. The effects of ADAC dosage, solution pH and temperature on flocculation were studied by measuring residual turbidity of the settled suspension. Moreover, the charge densities, sizes, ζ-potentials and stability of the ADACs in aqueous solutions were studied. The combined treatment was effective in the removal of colloidal particles, as demonstrated by reduced residual turbidity with remarkably lower total chemical consumption compared with coagulation with alum alone. Of the ADACs, samples with lower solubility that contained cellulose nanoparticles performed better than the fully water-soluble sample. Due to the restricted pH tolerance of alum, the combined treatment was effective only at acidic conditions (pH < 5), although the ADACs were found to be stable in a much broader pH range (pH of 3 to about 9). ADACs also retained strong activity at higher temperatures (30-60 °C) and after several days of storage in aqueous solution.