ASTM G75A Miller tester (Figure 1 )constructed in conformity to the ASTM G75 standard is used to measure (a) Miller Number for slurry abrasivity assesment and (b ) the slurry abrasion response (SAR) numbers of materials in a given slurry. If not specified, procedures spulated in the ASTM G75 standard are followed.

1. Slurry for machine calibraon/qualificaon is a mixture of AFS 50-70 silica sand and deionized water at 50wt% concentraon.2. Slurry for MIller Number test (slurry abrasivity) is either providei by the client in a pre-mixed form mixed at the NRC with solids and/ or liquid provided by the client according to the client’s requirements. 3. Slur 3. Slurry for the slurry abrasion response (SAR) test of materials can be the same as used in the MIller Number tests as mecon above (2) or, it not specified, mixed using AFS 50-70 silica sand and

Sliding speed: 48 rpmLoad: 22.5 N

Calibraon Test:At the beginning of each project, a calibraon test is conducted to confrim the working condions of the test machine. Slurry used in the calibraon/qualificaon is a mixture of AFS 50-70 silica sand and deionized water at 50wt% concentraon.Standard 27% chrome white cast iron wear specimens are used for the machine calibraon. These standard specimens were purchased from Falex Corporaon through Compass Instruments.

where M (in mg is the cumulave mass loss at the different sliding me, t (),in hr).

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Tesng Condions

Slurry:

The cumulave mass loss, M, is obtaiined by measuring sample mass changes at the three equally spaced 2 hr tesng intervals, i.e., at a total/ accumulave sliding me, t, and 6 hr respecvely. A curve fi ng is conducted for a relaonship between the cumulave mass loss , M, and sliding me, t, per the following equaon:

Calculaon of slurry abrasion response (SAR) numberThe basis test procedure for dtereminaon of SAR numbers are the same as those for obtaining the Miller Number as described in the above secon except the the SAR number calculaon is according to the following expression as define in the ASTM G75 standard,

DepartureSomemes, another parameter, departure, is calculated from the Miller od SAR number test which is defined as the percentage change of the mass loss rate. Departure is calculated by the following formula (ref. Eq. 3):

Negave (-) departure indicates that the abrasivity of the slurry decreases with the me, i.e., the slurry parcles wear out with the me. On the other hand, posive (+) departure shows an actual increase in abrasivity of the slurry with the me, meaning that breakdown/fracture of abrasive parcles in the slurry causes more severe wear than original abrasive parcles. This is important if the slurry is to be transported for a long distance.

This parameter is not specified by the ASTM G75 standard as mandatory in final report. However, it is calculated somemes to provide some addional insights into the abrasion characteriscs of the slurry.

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