Reaction mass of ditungsten carbide and tungsten carbide

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

N/A to 2009-05-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented, scientifically sound study that used appropriate measurement instrumentation. Work performed following cGMP. Report was reviewed by laboratory Quality Assurance Department. The reliability of this study for the substance tested is a K1, but in application of read-across to a different substance, ECHA's guidance specifies that the score can be a maximum of a K2.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Tungsten Carbide
Target: Fused tungsten carbide
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR

Reason / purpose for cross-reference:

read-across: supporting information

Principles of method if other than guideline:

The particle size was analyzed by the Malvern MasterSizer LASER diffracter. This instrument is an ensemble analyzer that calculates a volume distribution from the LASER diffraction pattern of a cloud of particles. This raw scatter data is then processed using a complex algorithm and presented on the basis of an equivalent spherical diameter. This instrumentation is approved by ECHA Guidance, 2008 (Chapter R.7a, pg. 148)

GLP compliance:

not specified

Type of distribution:

volumetric distribution

Key result

Percentile:

D50

Mean:

4.31 µm

Remarks on result:

other: Migrated from fields under 'Mass median diameter' as D50 percentile. No source field for Standard deviation.

Key result

Percentile:

D10

Mean:

1.86 µm

St. dev.:

0

Key result

Percentile:

D50

Mean:

4.31 µm

St. dev.:

0

Key result

Percentile:

D90

Mean:

9.74 µm

St. dev.:

0

No specific standard deviation were identified for the particle distribution data although significant robust data was presented in the laboratory report.

The B.E.T. Surface Area of the test substance sample was determined to be 0.21 m^2/g.

Conclusions:

The finest products are typically fractions 0-40 µm with a low percentage of less than 10 µm as seen by laser diffraction.

Executive summary:

Due to the similar chemical constituency and structure between the source substance (tungsten carbide) and the target substance (fused tungsten carbide), the physico-chemical properties would be expected to be the same or sufficiently similar such that application of read-across from tungsten carbide is appropriate for this endpoint. For more details, refer to the attached read-across approach document.

Description of key information

The finest products are typically fractions 0-40 µm with a low percentage of less than 10 µm as seen by laser diffraction.

Additional information

Due to the similar chemical constituency and structure between the source substance (tungsten carbide) and the target substance (fused tungsten carbide), the physico-chemical properties would be expected to be the same or sufficiently similar such that application of read-across is appropriate for this endpoint. For more details, refer to the attached read-across approach document.