Impurities and Detection Methods of Synthetic Diamond Micropowder

Domestic diamond micropowder mostly uses type I single crystal diamond as the raw material, but type I material has high impurity content and low strength, so it can only be used for the product demand of the low-end market. A small number of domestic diamond powder manufacturers use type II or type III single crystal diamond as raw material to produce diamond powder, and its processing efficiency is much higher than that of ordinary diamond powder, which can meet the high-end market demand.

Diamond powder has high hardness and good wear resistance, and is widely used in cutting, grinding, drilling, polishing and other fields. With the development and progress of science and technology, the market demand for diamond micropowder is increasing, and the quality requirements are also getting higher and higher. For diamond powder, the amount of impurities in diamond powder directly affects the product quality and performance of the powder.

 

1. Types of impurities in synthetic diamond powder

The impurities of diamond powder refer to the non-carbon components in diamond powder, which can be divided into external impurities and internal impurities. The external impurities of the particles are mainly introduced by the raw materials and the production process, including silicon, iron, nickel, calcium, magnesium, cadmium and other elements; the internal impurities of the particles are introduced by the diamond synthesis process, mainly iron, nickel, cobalt, manganese, cadmium, copper wait.

Impurities in diamond micropowder will affect the surface properties of the micropowder particles, making the product difficult to disperse. Impurities such as iron and nickel will also cause the product to produce different degrees of magnetism, which will affect the application of micro powder.

 

2. Impurity detection method of synthetic diamond powder

There are many methods for detecting the impurity content of synthetic diamond powder: including gravimetric method, atomic emission spectrometry, atomic absorption spectrometry, etc. Different detection methods can be selected according to different requirements during application.

 

1). Weight method

The gravimetric method is suitable for the analysis and detection of the total impurity content (excluding burning volatile substances at the burning temperature), and the main equipment includes muffle furnace, analytical balance, porcelain crucible, dryer, etc. The test method for impurity content in the micro powder product standard is the high-temperature ignition loss method: take samples according to the regulations, weigh the samples to be tested and put them into a crucible with constant weight, place the crucible with the samples to be tested in a muffle furnace for 1000 ℃ to constant weight (temperature allowed ± 20 ℃), the residue weight is the amount of impurities, and the weight percentage is calculated.

 

2) Atomic emission spectrometry, atomic absorption spectrometry

Atomic emission spectrometry, atomic absorption spectrometry, etc. are suitable for qualitative and quantitative analysis of trace elements.

 

(a) Atomic Emission Spectroscopy: It is an analytical method for qualitative or quantitative analysis of elements by using the characteristic radiation produced by the electron transition from the excited state to the ground state of atoms of various chemical elements excited by external energy. The atomic emission method can analyze about 70 kinds of elements. Under normal circumstances, it can accurately measure the trace elements in the ppm level in the diamond micropowder when it is used for the determination of the components below 1%. This method is the earliest one produced and developed in the optical analysis method. In the qualitative and quantitative analysis of various materials in modern times, atomic emission spectrometry has played an important role. It has the advantages of multi-element simultaneous detection capability, fast analysis speed, low detection limit and high accuracy.

(b) Atomic absorption spectrometry: When the radiation emitted by a specific light source passes through the atomic vapor of the element to be measured, it is absorbed by its ground state atoms, and elemental analysis can be carried out by measuring the degree of absorption.

Atomic absorption spectrometry and atomic absorption spectrometry can complement each other, not replace each other.