Characterization of Working Thicknesses of Some Bath-Dip-Produced Corrosion – Protective Bitumen Coatings on Polish-Prepared Low Carbon Steel Specimens
The coating thickness is an important variable that plays a role in product quality, process control and cost. Determination of the required working thicknesses for different service requirements is however a complicated task in the product finishing field. A previous study has shown that Nigeria is blessed with abundant bitumen resources for sustained exploitation as common, economical and effective coat-inhibitors of steelwork corrosion in her economy. This paper presents a testdetermination of the expected range of working thicknesses of coatings with proper bitumens from the resources. Bitumen samples were harvested at three different critical bitumen resource sites in the country for the tests. 30 specimens of the steel were properly prepared. Coatings of different thicknesses were produced on the specimens by dipping a different pair of them in each bitumen sample heated to each of five different temperatures in the range of 170 – 230 O C and removing and cooling them to 38 O C-room-temperature. The thickness of each produced coating was properly determined with a micrometer through dimensional change before and after coating. Analysis of the overall obtained data shows that the average working thicknesses of coatings with any bitumens of comparable quality to the as-harvested from the resources using temperatures in the range will decrease with increase in temperature from about 1.46 to 0.81mm respectively, and thicknesses of coatings with the separate bitumens using the same bath temperature will have minimal variations.
Assessment of Physicochemical Properties of some Bitumens from Nigerian Resources
Bitumen is a cheap, common, and important material in today’s technological world. Bitumens gotten at different locations on earth, and produced from different manufacturing processes, or crude feedstocks can however have wide variations in physico-chemical properties and levels of service performances. Hence reliability, handling, and modification in technological usage of different bitumens demands that proper information on a given harvested one should be consulted. Nigeria has large reserves of natural bitumen resources and potentials for sustained production of bitumen in large quantity, but basic applicable public information is lacking on bitumens at most locations of the resources. In this paper, proper test-obtained result of the properties is presented for three bitumen samples obtained from some important sources in the country. Assessment of the results vis-a-vis available information on bitumens elsewhere indicate that any clear surface or underground natural bitumen obtainable in the region of Agbabu village in Ondo State, and a manufactured type from Kaduna Refining and Petrochemical Company (KRPC) in the country are comparable with bitumens of good or acceptable qualities from other locations in the world. Bitumen from the region and the as-manufactured are therefore recommended to be producing in large available quantity and exploiting for different technological applications.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.