Abrasion index

The AI is determined by filling a 2-kg coal sample into a pot, which is equipped with an internal stirrer consisting of four medium-carbon steel blades. 

The stirrer is agitated for 12 000 revolutions with a speed of 1450 min . The mass loss of the blades is then divided by the sample mass yielding the AI in mg/kg. The AI for coal is reported in the range of 10 to lOOmg/kg [43,125,126]. 

---

Ablators, in tumescent Ablators, melting Ablators, subliming Abortifacients Abortion, habitual AB polyamides Abrasion index Abrasion tests Abrasive... 

The drop shatter test indicates the resistance of a coal or coke to breakage on impact (see D440). A sample is dropped in a standard way a number of times from a specified height. Eor the tumbler test or abrasion index (ASTM D441), the coal or coke is rotated in a dmm to determine the resistance to breakage by abrasion (18). 

An abrasion index in terms of kilowatthour input per pound of metal lost furnishes a useful indication. Rough values are quoted in Table 20-3. 

Material Number tested Product diameter, im Work index E. Average abrasion index A,... 

Linear regression analysis was performed on the relation of G"(s) versus PICO abrasion index. Figure 16.10 plots the correlation coefficient as a function of strain employed in the measurement of loss modulus. The regression results show poor correlation at low strain with increasing correlations at higher strains. These correlations were performed on 189 data points. 

Solution random copolymers prepared by the above procedures have performed well in tire-tread formulations. 22 They require about 20 percent less accelerator (see Table II) as compared to an emulsion SBR and give higher compounded Mooney, lower heat buildup, increased resilience and better retread abrasion index. 

Whichever approach you take, the result is still dependent on the variability of the standard rubber and, arguably, it could be better to rely on the reproducible manufacture of, for example, an abrasive wheel. It would not seem beyond the bounds of ingenuity to find a standard material which is inherently more reproducible than rubber It could then be used either to certify the abradant or to use in the calculation of abrasion index. 

Results can either be expressed as a relative volume loss with the abradant normalized relative to a standard rubber or as an abrasion index relative to a standard rubber. The former is the original German approach and the latter is that approach favoured by, for example, British standards. Two standard rubbers are specified which originate from the German and British standards. This is a fine example of the chicken and egg problem of standard rubber and abradant. To understand the situation it must be appreciated that an accurately specified standard abradant has been available in Germany for many years, but the rubber used to check it has a formulation of no relevance to real products and is very difficult to reproduce in laboratories other than that of its origin. The British standard rubber is based on a tire tread and, hence, has practical relevance. 

Either way of expressing results can be used with either rotating or nonrotating test pieces but, normally, only the German standard rubber would be used with relative volume loss. In previous versions, only the abrasion index approach had the option of using a rotating test piece. 

The Pico abrader is specified in D222857. This device uses a pair of tungsten carbide knives which rub the test piece whilst it rotates on a turntable. The direction of rotation is reversed at intervals throughout a test and a dusting powder is fed to the test piece surface, which doubtless helps to avoid stickiness. The apparatus is calibrated by the use of no less than five standard rubbers and the result also expressed as an abrasion index. Force on the test piece and speed of rotation can be varied and, presumably, different abradant geometries could be used, although the distinctive feature of the Pico is the use of blunt metal knives in the presence of a powder. 

In car tire development, an optimal combination of three-component composition has been researched Xi-hydrated silicate, PHR X2-silan, PHR and X3-sulfur, PHR. These parameters were measured as system responses yi-PICO abrasion index y2-200% module y3-strain at brake and y4-hardness. The experiment has been done in accord with CCRD. Experimental outcomes are shown in Table 2.163. Determine regression coefficients values for all four responses. 

T Abrasion index is the fraction of a gram weight lost by the standard steel paddle in 1 h of beating 1600 g of Va- by V -in particles. The product averages 80 percent passing 13, 0 lm. 

Test places Main factors for abrasion Abrasion Index (% )... 

Abrasion Index = (Abrasion of the design on the soles of the trial shoes) / (Abrasion of the design on the soles of the commercial shoes) x 100... 

The best way of assessing abrasiveness is to use the actual bulk material and the contact surfaces in question. One such test was developed by Yancey, Greer and Price61 and has been adopted in a British Standard for coke and coal62. From the test, another abrasiveness index is determined by measuring the wear on a standard surface when the surface is brought into moving and intimate contact with the coal under specified conditions. 

---