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PMI - COMPARING TWO TEST METHODS: XRF & OES

The production of standard alloys is an extremely essential element because standard types of alloys will provide safety as well as efficient operation, and also have a long shelf life and bring more economical, therefore the quality control of these alloys is extremely important.

With Positive Material Identification (PMI) the alloy composition, and thus, the identity of materials can be determined. If a material certificate is missing or/and you need to be certain about the type of material used. Because specifications for materials used in industry are increasingly more specific, the need for PMI testing has been steadily increasing. XRF and OES types of PMI are available, and both analysis techniques offer advantages and disadvantages.

Method

X-ray Fluorescence (XRF)

Optical Emission Spectroscopy (OES)

Principles

Instruments work by exposing a sample to be measured to a beam of X-rays. The atoms of the sample absorb energy from the X-rays, become temporarily excited and then emit secondary X-rays. Each chemical element emits x-rays at a unique energy. By measuring the intensity and characteristic energy of the emitted X-rays, the analyzer can provide qualitative and quantitative information regarding the composition of the material being tested.

Using an electrical source to excite atoms within a metallic sample so that they emit characteristic light, or optical emission, lines – requires a small part of the sample to be heated to thousands of degrees Celsius. This is done using an electrical high voltage source in the spectrometer via an electrode. The difference in electrical potential between the sample and electrode produces an electrical discharge, this discharge passes through the sample, heating and vaporizing the material at the surface and exciting the atoms of the material, which then emits the element-characteristic emission lines.

Sample

Liquid, powder, solid ...

Mainly alloy and metal

Preparing of surface sample

No need or simply

Need grinding, lathe ... depending on the type of alloy

Analytical range

Wide, but not or difficult to analyze light elements like C (carbon)

Wide, easy to analyze light elements with high accuracy and low detection limits

Analytical environment

Air, helium or vacuum

Argon, can be analyzed without argon environment but not accuracy

Application

Widely available in many application such as electricity, electronics, mining, pharmaceuticals, petrochemicals ...

Metallurgy, casting, automotive…

Equipment

EDX-7000

http://www.tecotec.com.vn/en/xray-fluorescence-spectroscopy/

PDA 5000

http://www.tecotec.com.vn/en/optical-emission-spectroscopy/

 Source: ETA

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