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Introduction & Principle
Positive Material Identification (PMI) is the
testing tool used to identify the materials by
detecting the alloy composition. Some of the
elements that can be identified using PMI are Ti, V,
Cr, Mn, Co, Fe, Cu, Zn, Ni, Se, Nb, Mo.
There are two type of PMI methods used, one is X-ray
fluorescence and the other one is Spark emission
spectrography.
For X-ray fluorescence type, the equipment contains
either radioactive sources or X-ray tube, which
sends out radiation. The exposed material then sends
temporarily element specific radiation back,
generating energy. As every element has its own
atomic structure, this reflection will generate a
different energy level for every element. This
energy is measured and detected and thus identifying
the alloy elements. The advantage of the XRF method
is used to execute without damaging the material,
easy for operation and result available immediately.
Spark emission Spectrography is based on optical
emission. The equipment consists of a probe which
releases a spark that is used to vaporize the
material being analyzed. The atoms and ions in this
vapor produce a spectrum which can be optically
measured and then recalculated to determine the
components of the material.
Application
PMI is applied whenever the customer required the
certainty of composition of the material or whenever
the material test certificate is not available. PMI
is one of the major testing tools used on
construction projects.
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