Reaction mass of ditungsten carbide and tungsten carbide

Auto flammability

Link to relevant study record(s)

Reference

Endpoint:

relative self-ignition temperature (solids)

Type of information:

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

Adequacy of study:

key study

Study period:

2010-06-30 to 2010-08-12

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP study, conducted according to N.4 in Part III, subsection 33.3.1.6 of the United Nations Recommendations on the Transport of Dangerous Goods-Manual of Tests and Criteria 4th Revised Edition. Detailed sample characterization was included. 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

Qualifier:

according to guideline

Guideline:

other: to N.4 in Part III, subsection 33.3.1.6 of the United Nations Recommendations on the Transport of Dangerous Goods-Manual of Tests and Criteria 4th Revised Edition.

GLP compliance:

yes

Key result

Relative self-ignition temperature:

> 140 °C

Remarks on result:

other: 100 mm cube at 140 °C

100 mm cube at 140 °C = no ignition

None of the test substance samples ignited during the test. Furthermore, the sample temperature for all three test substance samples never exceeded the oven temperature by 60 °C. Therefore, it can be concluded that tungsten carbide is not a self-heating substance at the particle sizes tested.

Conclusions:

None of the test substance samples ignited during the test. Furthermore, the sample temperature for all three test substance samples never exceeded the oven temperature by 60 °C. Therefore, it can be concluded that tungsten carbide is not a self-heating substance at the particle sizes tested.

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 this read-across is appropriate for this endpoint. For more details, refer to the attached read-across approach document.

Description of key information

The auto-flammability/self-heating of fused tungsten carbide is expected to be the same as/similar to tungsten carbide.  Three samples of tungsten carbide were tested in a standard test for self-heating. None of the test substance samples ignited during the test.  Furthermore, the sample temperature for all three test substance samples never exceeded the oven temperature by 60°C. Therefore, it can be concluded that tungsten carbide is not a self-heating substance at the particle sizes tested. Testing was conducted down to a particle size of 0.53 µm (FSSS size) (nominally 0.47 µm).

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 this read-across is appropriate for this endpoint. For more details, refer to the attached read-across approach document.