Methods for analyzing and testing the composition of metallic materials have evolved over time, moving from traditional titration and spectrophotometry to more advanced techniques such as plasma emission spectrometry and spark direct reading spectrometry. The testing process has also changed, allowing simultaneous analysis of multiple elements, which has improved efficiency and accuracy. The principles and characteristics of different testing methods are as follows:
1. Spectrophotometry
Spectrophotometry is a widely used method for quantifying metallic elements. It involves measuring absorbance and light intensity within a specific wavelength range to perform qualitative and quantitative analysis. This method is known for its wide application, high sensitivity, good selectivity, high precision and low cost, but it has the disadvantage of being able to analyze only one element at a time. Detection instruments used in spectrophotometry include ultraviolet spectrophotometers, visible spectrophotometers, and infrared spectrophotometers.
2. Titration
Titration is a method of testing metallic components in a solution with a standard concentration of reagents. The metallic components react completely with the reagents to reach the end point of the titration. This method can be used to test substances with a content greater than 1%, but has the disadvantage of being low in efficiency.
3. Atomic spectrometry
Atomic Absorption Spectrometry (AAS) and Atomic Emission Spectrometry (AES) are traditional technologies used to analyze the composition of metallic materials. AAS uses the principle of quantifying the content of analyzed elements by measuring the absorption intensity of external electrons from ground state atoms in the gaseous state to the corresponding atomic resonance radiation line of visible light and ultraviolet light. This method is ideal for gaseous atomic absorption radiation and is characterized by high sensitivity, strong anti-interference ability, strong selectivity, wide analysis range and high precision. However, it has limitations such as the inability to analyze multiple elements simultaneously, low sensitivity in determining insoluble elements and low performance in measuring complex samples. AES, on the other hand, is based on the principle that each element, ion or atom emits specific electromagnetic radiation when subjected to electrical or thermal excitation. This method uses emitters for qualitative and quantitative analysis of elements and can test multiple elements at the same time with a smaller sample requirement and faster results. However, it has low accuracy and is only used to analyze metallic components and cannot be applied to most non-metallic components.
4. X-ray fluorescence spectrometry
X-ray fluorescence spectrometry is widely used for the determination of metallic elements and is a common method for analyzing the composition of metallic materials. The principle of the test is based on the fact that atoms in their ground state are in a low-energy state, but once excited by radiation of a certain frequency, they enter a high-energy state and emit fluorescence. The wavelength of this fluorescence is unique and by measuring these X-ray fluorescence spectral lines, the type of elements in the sample can be determined. Element content can be estimated by comparing the intensity of the sample's spectral lines with the reference spectral lines of a standard sample. This method is a qualitative and semi-quantitative approach mainly used to approximate the content of metal composition analysis.
5. Inductively coupled plasma spectrometry
Inductively coupled plasma atomic emission spectrometry (ICP-AES) is currently the most widely used method. Its principle is to excite metallic elements, causing electronic transitions that result in the emission of spectral lines with certain intensities that are used to determine the elements and their concentrations. This method has a wide range of applications, is highly sensitive, has fast analysis speed and provides high accuracy. It can test a batch of samples simultaneously and determine multiple elements under one marking line.
6. Spark Direct Read Spectrometry
The Spark direct reading spectrometer uses electrical arcs or high-temperature sparks to directly vaporize and excite elements in a solid-state sample, causing them to emit characteristic wavelengths. These wavelengths are then divided using a grid, producing a spectrum organized by wavelength. Spectral lines characteristic of the elements pass through the exit slit and enter their respective photomultiplier tubes, where the optical signal is converted into an electrical signal. The control and measurement system integrates the electrical signal, which is then processed by a computer to determine the percentage content of each element. This method is highly accurate and can simultaneously analyze multiple elements, with qualitative and quantitative results for dozens of elements obtained in a single excitation and analysis. It is fast, efficient and does not require expensive chemical reagents or special excipients. Direct testing of solid samples is possible. However, the sample format and size have certain requirements.
7. Carbon and sulfur analysis
In metallic materials, especially steel metals, carbon and sulfur are the primary elements that require testing, and the above-mentioned methods cannot accurately quantify carbon and sulfur. As a result, carbon and sulfur elements need to be tested using a carbon and sulfur analyzer. The sample is subjected to high-temperature heating under oxygen-enriched conditions, oxidizing the carbon and sulfur to carbon dioxide and sulfur dioxide. After treatment, the gas enters the appropriate absorption pool, absorbing the corresponding infrared radiation, which is transmitted by the detector as a signal. The computer processes the signal and produces the results. This method is accurate, fast and sensitive and can be used to analyze high and low levels of carbon and sulfur content.
8. Oxygen and nitrogen analysis
The oxygen and nitrogen analyzer is used to measure the oxygen and nitrogen content in various steels, non-ferrous metals and new materials. It decomposes the sample by pulsed heating under an inert atmosphere and measures the contents with an infrared detector and a thermal conductivity detector, respectively. This method is known for its high accuracy and low detection limit.
Introduction to Test Items
| Metal category | Project | ||
| Iron and Steel | Element analysis | Grade Identification (to identify whether it conforms to a standard or grade) Request) | Coating composition analysis (testing of coating composition and elementElement content) |
| High purity copper/copper alloy | |||
| Lead-free solder/leaded solder | |||
| aluminum alloy | |||
| magnesium alloy | |||
| Kirsite | |||
| titanium alloy | |||
| Precious metals (gold, silver, palladium, platinum) | |||
| High purity metal | |||
| Brazing filler metal | |||
| powder metallurgy | |||
