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HfCl4 is not considered as a self-reactive substance.
HfCl4 is considered as corrosive to metals.

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Considering the chemical structure of the substance and taking Appendix 6 for self-reactive substances (especially Table A6.1 and Table A6.2) of the UN guidelines for the use of screening procedures into consideration, Hafnium Tetrachloride is considered not to contain any chemical groups indicating self-reactive properties.

Corrosity to metals:

A substance or a mixture that is corrosive to metal under normal conditions is a substance or a mixture liable to undergo an irreversible electrochemical reaction with metals that leads to significant damage or, in some cases, even to full destruction of the metallic components. According to the classification criteria (CLP Annex I, only substances and mixtures for which the application of the test “C.1”described in part III, section 37 of the UN-MTC (4th revised edition) is relevant and needs to be considered. This means that non soluble solids are excluded, while “liquids and solids that may become liquids (during transport)”, as mentioned in this reference text, have to be considered for such a classification. It is recognised that solids with a melting point > 55°C are difficult to test according to the current CLP requirements, as the advised test has been designed for liquids. Besides, Hafnium Tetrachloride, hydrolyses immediately in contact with water, releasing hydrogen chloride. Thus, this test is technically not feasible for HfCl4. However, Hydrogen chloride is a Class 8 (corrosive) substance as defined by the UN. Based on this potential to release hydrogen chloride, Hafnium Tetrachloride is concluded to be corrosive to skin (see section 7.3.1). The corrosive potential of Hafnium Tetrachloride thus depends on the amount of hydrogen chloride released during the time period it is in contact with metal(s).Based on the above, it is concluded that the substance itself is not corrosive to metals, however the release of hydrogen chloride with moisture will provide a corrosive environment in and around the material. Hafnium Tetrachloride is therefore concluded in daily handling and use not to be compatible with metals and should thus be classified as corrosive to metals.