Weighing of specimens

For accuracy of weighing, it is usually necessary to restrict the dimensions of specimens to what can be accommodated on the common analytical balances. It must be borne in mind that where attack occurs in the form of a very few pits or in crevices under supports, the extent of this localised  [c.979]

The most precise measurements of corrosion resistance require the use of specimens that can be weighed accurately after careful removal of corrosion products by the techniques described earlier.  [c.1069]

Specimens should be finally degreased by scrubbing with bleach-free scouring powder, followed by thorough rinsing in water and in a suitable solvent (such as acetone, methanol, or a mixture of 50 percent methanol and 50 percent ether), and air-dried. For relatively soft metals such as aluminum, magnesium, and copper, scrubbing with abrasive powder is not always needed and can mar the surface of the specimen. The use of towels for drying may introduce an error through contamination of the specimens with grease or lint. The dried specimen should be weighed on an analytic b ance.  [c.2426]

The final step in surface preparation should ordinarily be a cleaning and degreasing treatment to remove any dirt, oil or grease that might interfere with the inception or distribution of corrosion. The simplest test of a satisfactory surface condition in this respect is for the specimens to be free from water break when rinsed with water after cleaning. As a final treatment for specimens to be weighed prior to exposure, a dip in a mixture of water and acetone or of alcohol and ether will facilitate quick drying and avoid water-deposited films. Specimens to be stored prior to weighing should be placed in a desiccator which, in best practice, should be sealed without grease  [c.979]

For preliminary tests where the number of test specimens that can be accommodated is limited, yet numerous materials are of possible interest, it is in order to expose single specimens. This may be more advantageous than limiting the compositions that can be investigated by exposing half the number of materials in duplicate. Probably the greatest advantage in exposing two specimens of a material instead of only one is in detecting gross errors, as in weighing, etc. rather than in any considerable improvement in the precision of the observations that may be made as to the relative behaviours of the metals tested.  [c.981]

Test work for the materials and coating program and the basic erosion parameter test program was conducted in specially designed test rigs. Eigure 4-124 schematically shows the general arrangement. A microblaster feeds the weighed sample of particulate nozzle, which directs the erosive particle to the erosion specimen. A vacuum line transports the dusty air from the test chamber to a filter system where all particulate matter is removed from the air. The basic method Elliott employed for determining the amount of damage to the specimens was weight loss. This required precise measurements of weight. A balance  [c.248]

Many methods of air quality me.asurement have inherent averaging times. In selecting methods for measuring air quality or assessing air pollution effects, this fact must be borne in mind (Table 4-1). Thus, an appropriate way to assess the influence of air pollution on metals is to expose identical specimens at different locations and compare their annual rates of corrosion among the several locations. Since soiling is mainly due to the sedimentation of particulate matter from the air, experience has shown that this can be conveniently measured by exposing open-topped receptacles to the atmosphere for a month and weighing the settled solids. Human health seems to be related to day-to-day variation in pollutant level. It is accepted practice the world over to assess suspended particulate matter levels in the air by a 24-hour filter sample, which in the United States is acquired by a high-volume sampler, known to workers in the field as a hi-vol.  [c.47]

Diamond is the hardest and least perishable of all minerals, and these qualities, coupled with its brilliant sparkle, which derives from its transparency and high refractive index, make it the most prized of gemstones. By far the largest natural diamond ever found (25 January 1905) was the Cullinan it weighed 3106 carats (621.2g) and measured 10 X 6.5 X 5cm (the size of a man s clenched fist). Other famous stones are in the range 100 - 800 carats though specimens larger than 50 carats are only rarely encountered. Most naturally occurring diamonds, however, are of industrial rather than gem-stone quality. They are used as single-point tools for engraving or cutting, and for surgical knives, bearings and wire dies, as well as for industrial abrasives for grinding and polishing. Other uses are as thermistors and radiation detectors, and as optical windows for lasers, etc.  [c.272]

For these reasons, it is much better to determine the amount of metal removed by corrosion by weighing what is left after removal of all adherent corrosion products by some method that will not cause further attack in the process, or by making a proper correction for losses in the cleaning process. (Removal of corrosion products is dealt with in detail in Appendix 19.1 A.) Subtracting this final mass from the original mass will give the loss in mass during the test. Since the extent of this loss in mass will be influenced by the area exposed, as well as by the duration of exposure, it is desirable, in order to facilitate comparisons between different tests and different specimens, to report the loss in mass in a unit which includes both area and time. A most commonly used unit of this sort is milligrams weight loss per square decimetre of exposed surface per day (24 h) (mdd).  [c.987]

This test, which is frequently referred to as the Huey test, was first described and used by W. R. Huey in 1930, and since that time it has had wide application, particularly in the USA. The test consists of exposing the specimens (20-30 cmin fresh boiling 65% HNO3 (constant boiling mixture) for five successive periods of 48 h each under a reflux condenser. The specimens are cleaned and weighed after each period, and the corrosion rate (as a rate of penetration) is calculated for each period of test and for the average over the five periods corrosion rates are expressed as mm/y. The reason for the  [c.1033]

Whatever cleaning method is used, the possibility of removal of solid metal is present. This will result in error in the determination of the corrosion rate. One or more cleaned and weighed specimens should be recleaned by the same method and reweighed. Loss due to this second treatment may be used as a correction to that indicated by the first weighing.  [c.1095]

See pages that mention the term Weighing of specimens : [c.1085]    [c.249]    [c.175]   
Corrosion, Volume 2 (2000) -- [ c.5 , c.13 , c.14 , c.19 ]