Abstract： Grinding paste is a kind of surface precision machining. The surface roughness of the workpiece can be improved by using the grinding effect of abrasive paste. The diamond grinding paste is used to grind hard and brittle materials for a high surface finish. How to use diamond grinding compound? The following is the introduction and usage of diamond grinding paste.

Introduction to diamond grinding paste

The diamond abrasive paste is finely formulated with fine diamond powder and other raw materials. It is an ideal abrasive paste for grinding and polishing. It has good lubrication and cooling properties. The diamond particles in the diamond compound have high hardness, uniform particle size, and a good grinding effect.

Diamond grinding pastes are made of high-grade large-grain diamond crystals as raw materials, and the most advanced powder preparation technology is used to sort out the diamond powder with extremely narrow particle size distribution (nano and micron). Strictly controlled nano and micro level single-crystal diamond crystal shape control system, so that the approximate circle value of each particle is almost perfect, successfully participates in the grinding and polishing process and obtains higher quality reproducibility. The diamond with a self-lubricating function is evenly distributed in the paste carrier. It can quickly polish metallographic sample materials with irregular surfaces (grooves, etc.), which is easy to use.

The characteristic of diamond abrasive paste is that the abrasive continuously rolls during the grinding process, producing two functions of extrusion and cutting, so that the convex and concave surface gradually becomes smooth and smooth.

Types of Diamond Paste

（1）Classification by solvent

The oil-soluble diamond paste has good wettability, low grinding force and grinding heat. It is mainly used for load mechanical grinding and processing high-quality carbide, high-carbon steel and other high-hard alloy parts, such as instruments, measuring tools, Cutting tools, abrasive tools, etc.

The Water-soluble diamond paste has low viscosity, easy removal, and high processing efficiency. It is mainly used for fine grinding of metallographic and petrographic samples, such as circuit boards, glass, ceramics, gems, agate and other non-metallic hard and brittle materials.

（2）Classification by diamond micropowder

According to the difference of the diamond powder used, it can be divided into polycrystalline diamond paste and single crystal diamond paste. Different from single-crystal diamond abrasive paste, polycrystalline diamond abrasive compound uses polycrystalline diamond powder as the main abrasive, which has strong self-sharpening properties and can meet the high standards of customers. It can also be seen from the color that the polycrystalline diamond paste is black.

Selection of diamond paste

The selection of diamond paste is mainly based on the finish requirements and processing efficiency of the workpiece, as well as the original finish of the workpiece. If the margin is large and the processing efficiency is high, the coarser grain size can be selected. if the margin is small and smoothness is required, the finer grain size can be selected. Therefore, rough grinding and fine grinding are generally selected according to the requirements of the workpiece finish. Refer to the following table:

The selection of diamond paste is mainly based on the finish requirements and processing efficiency of the workpiece, as well as the original finish of the workpiece. If the margin is large and the processing efficiency is high, the coarser grain size can be selected. if the margin is small and smoothness is required, the finer grain size can be selected. Therefore, rough grinding and fine grinding are generally selected according to the requirements of the workpiece finish. Refer to the following table:

（1）Selection of monocrystalline diamond grinding paste

（2）Selection of  polycrystalline diamond grinding paste

Application of the Diamond paste

The synthetic diamond compound is a soft abrasive paste made of selected high-quality diamond micro-powder abrasives and paste-like binders, preservatives, flavors, etc. It is suitable for measuring tools, such as glass, ceramics, gemstones, hard alloys, and other high-hardness materials. Grinding and polishing of cutting tools, optical instruments, and other high-finish workpieces. It is also suitable for special-shaped workpieces made of the above-mentioned materials that are difficult to process with a grinding wheel tool.

How to use diamond paste

Grinding paste is a type of surface finishing. Use the grinding effect of the abrasive paste to improve the surface roughness of the workpiece. How to use diamond paste?

According to the material and processing requirements of the workpiece, select the appropriate grinding device and grinding paste. Commonly used grinders are blocks and plates made of glass, cast iron, steel, aluminum, plexiglass and other materials, and kerosene is used as the diluent.

During manual polishing, the diamond paste should be applied to the polishing tool. During mechanical polishing, the abrasive paste should be applied to the workpiece. The pressure used during polishing, the hardness of the polishing tool and the grade of the abrasive paste should be adjusted and adapted to each other. When performing fine polishing, the pressure should be adjusted to be equivalent to the weight of the polishing tool.

1. Diamond grinding is a kind of precision processing. During the processing, the environment and tools are required to be clean. The tools used must be dedicated for each particle size and must not be mixed.
2. The workpiece must be carefully cleaned before changing to different grit abrasive compounds during processing, so as to prevent the coarse particles from the previous process from being mixed into the fine grit abrasive paste to scratch the workpiece.
3. When polishing, squeeze a small amount of grinding paste into the container or directly squeeze it on the grinding device, and dilute it with a mixture of glycerin and distilled water at a ratio of 1:1. It can also be adjusted according to on-site use.
4. After polishing, the workpiece should be cleaned with gasoline or kerosene.

Storage of Diamond Paste

1. Do not squeeze during transportation and storage.
2. The storage room temperature should be below 20oC.
3. Store in a hygienic, cool and dry place.

Crownkyn superhard grinding and polishing material series are all preferred diamond abrasives. The advanced preparation process ensures that the high-quality particles are in an equal volume shape and the strict grading process ensures a high proportion of the final particle size and the uniformity of the particle size composition. The particle size range requirement is higher than the national standard.

Crownkyn Superhard diamond abrasive compound has a complete range of particle sizes and varieties, which can meet various requirements of users.

17nm polycrystalline nanodiamond is a kind of ultra-fine and ultra-dispersed nano-sized diamond (UFDD) prepared by special processes. This nanodiamond can be suspended in water for a long time without precipitation. The particle size distribution can be divided into two types: finer than 17nm the other is finer than 10nm.

Transmission Electron Microscopy (TEM)

1)17nm

2）10nm

From the TEM the particles are spherical, single-particle size is less than 10nm, at 4-6nm, and it is a polycrystalline structure. The TEM pictures are taken when water is the dispersion medium, when taking a picture the required state is dry therefore the agglomeration state is displayed. But in the water solution-state, the particle size smaller than 10nm can be displayed with good dispersion.

Particle Size Distribution (PSD)

We use the dynamic light scattering principle device to test the particle size, device name and model is Dandong Baite Bt-90(+) nano size analyzer. The specific particle size detection results are as follows:

1)17nm

Test Results Report of Nanometer Laser Particle Size Distribution Instrument

2）10nm

Test Results Report of Nanometer Laser Particle Size Distribution Instrument

Analysis of Test Results

• 10nm: the detection concentration is O.65%, the particle size is concentrated in 6.5 nm to 10.6 nm, the particle concentration n=(D90-D10)/D50=0. 325, the particle concentration is high, D50=8.2 nm, the volume average value D [4, 3] =8.25 nm, the area average value D[3, 2]=8.13, which is very close, indicating that the particle morphology is relatively smooth.
• 17nm: the detection concentration is 1%, the particle size is concentrated in 10.1 nm to 17.2 nm, the particle concentration n=(D90-D10)/D50=0.364, the particle concentration is high, D50=12.9 nm, the volume average value D[4, 3 ]=13 nm, the area average value D[3, 2]=12.8 nm. The three values are close to each other, indicating that the particle morphology is relatively smooth.

X-ray Diffraction (XRD)

The XRD results show that the diffraction peaks at 43.7°, 75°, 90° are matched with the (111), (220) and (311crystal faces of the diamond phase, indicating that the phase composition of the material is the diamond phase.

Fourier Transform Infrared Spectrometer (FTIR)

From the FTR spectrum, it can be seen that the surface of the nano diamond is rich in hydrophilic OH functional groups, which is conducive to composite with other materials and surface modification.

UV-vis

The pictures show the effect picture of 10nm and 17nm nano diamond suspension with a laser pen. It can be seen from the picture that the nano diamond suspension is evenly dispersed and has an obvious Dingdar Effect. It is a kind of colloidal solution. The dispersion of the system is stable and can be kept stable for a long time. Up to now, it has been standing for 15 months without agglomeration and precipitation, and the PH value of the dispersed solution is low 7, neutral.

Samples Picture

10nm&17nm

In order to meet the use of diamond sintering tools, diamond powder need to be performance tested. The main Material Properties of Diamond are wear resistance, thermal stability, impact strength and microstructure.

Diamond Shaped Detection System

people usually analyze the shape of Diamond Powder through naked eye observation under a microscope. Such an analysis has a lot of subjective factors, which will cause analysis deviation. The advanced shape detection system can quantitatively evaluate the quality of diamond crystal shapes.

Basic method: By scanning the diamond sample made of diamond particles perspective digital image plane (2-d) topography measurement in the scanner, then through the computer software to detect and analyze the image, to accurately measure the diamond morphology parameters and quantify them. Such as，shape，size, color, light transmittance, purity and morphology parameters, roughness, etc.

Diamond Shaped Detection System can include the following indicators: Fe (ellipticity), Fc (roundness), R%(roughness), PSD (particle size distribution), RGB (chromaticity), T (transparency), C (purity) and PPC (grain /ct). Under the use of the diamond shaped detection analysis system, the above indicators and morphology characteristics of the diamond have a scientific and detailed understanding, in order to use different types of diamond in the appropriate diamond tools, to achieve more targeted and efficient use of diamond.

Diamond Size Distribution Detection

The particle size distribution of diamond was determined by Laser Diffraction Analysis, the diffraction effect of light is produced when the laser is irradiated on the micro powder particles. The size difference of the particles brings the change of the laser diffraction angle, and the projection on the detector shows the change of the size of the diffraction ring. Laser Diffraction Particle Size Analyzer can be based on the size of the ring to analyze the size of the particle size, according to the strength of the ring to judge the number of a certain particle size.

Then by the computer according to the size of the diffraction ring and the strength of light, according to the predetermined mathematical relationship of fitting approximate analysis,

Then the computer performs Curve Fitting analysis according to the predetermined mathematical relationship, which is based on the size of the diffracted halo and the intensity of the light, to obtain the analysis result of the particle size composition of the sample.

The laser particle size analyzer can be used for the analysis of the particle size composition of the diamond powder. In order to better observe the particle size distribution of the diamond powder more intuitively, Metallography Observation is needed to observe the particle size of the diamond powder. The laser particle size analyzer can truly and effectively reflect the change of particle size composition, but it is not suitable for quality control of diamond powder. For diamond quality control, further strength testing is needed.

Diamond Strength Grade Inspection

Raman Spectroscopy is a kind of light scattering technique in which photons interact with the electron cloud and molecular cloud in the material molecules when the material is irradiated by the laser light source. It can provide detailed information about the chemical structure, phase morphology, crystallinity and molecular interaction of the sample.

Under the irradiation of the laser, Diamond powder and Diamond grains produce the Raman spectrum corresponding to its crystal structure, and at the same time also emits the corresponding fluorescence spectrum. Using the diamond Raman spectrum analyzer, the Raman spectrum and fluorescence spectrum information of the diamond material can be measured. Through the analysis of the Raman and fluorescence spectrum information, the strength grade of diamond powder can be judged.

Raman spectrum is a kind of molecular spectrum. The SP3 hybrid orbital formed between carbon atoms in the molecular structure of diamond determines the intensity of Raman peak at the 1330 wave number of diamonds. The more SP3 hybrid orbital formed, the more complete it will be, and the greater the intensity of 1330 spectrum peak will be, while the vice versa. The more the internal impurities and the greater the stress in diamond crystal, the higher the fluorescence spectrum intensity, and vice versa.

Diamond Impact Toughness Testing

In the process of use, diamond particles, especially high-grade diamond particles used in sawing and drilling, are often destroyed due to impact in bad working conditions and large movement impact force, and the strength of diamond cannot be fully weighed by the static compressive strength alone. Therefore, it is required to have a certain Impact Toughness of Diamond Grits. Impact toughness tester is a special instrument for testing the impact strength of diamond. In the production process of diamond tools, in order to guarantee and improve product quality, toughness test of diamond should be done to know about what type of diamond tools the current batch of diamond is suitable for, and to tailor the diamond tools according to the requirements. The test device of diamond impact toughness is shown in the figure below.

Thermal Toughness Index (TTI) of diamond is an index to measure the thermal impact toughness of diamond, which reflects the thermal stability of diamond under high temperature working conditions. The performance of diamond tools at higher temperatures (such as dry saw blades or poor cooling) has a great influence on the performance and life of diamond tools. Diamond thermal toughness index tester is a special instrument for measuring the impact toughness of diamond particles at high temperature.

Diamond Magnetic Susceptibility Testing

When Synthetic Diamond at high temperature and high pressure, metal alloys such as Fe, Co, Ni, Mn are often used as catalysts to promote the nucleation and growth of diamond. A small amount of catalyst as an impurity is wrapped in the diamond particles during the growth of diamond, causing internal defects of the diamond. At the same time, it is affected by high temperature during manufacturing and using, causing diamond abrasive grains to crack, and the strength drops sharply. Therefore, in the diamond production process, diamond abrasive grains with different magazine contents must be separated, and the impurity content of the diamond must be detected.

The impurities in diamond are basically ferromagnetic substances and the amount of impurities can be determined indirectly by the method of magnetic testing. The magnetism of diamond is characterized by its magnetic susceptibility, which reflects the content of impurities and inclusions in the diamond and is closely related to the thermal impact strength and other technical indicators of diamond.

Diamond Bulk Density

Bulk Density of Powder refers to the weight of abrasive grains contained in per unit volume of air when the abrasive is stacked, in g/cm³. It is the most commonly used physical quantity to indicate the filling characteristics of powder objects, and it is also a comprehensive reflection of the physical properties of diamond density, particle shape, surface state and particle size group composition. It is a general method for testing the physical properties of the material in the world.

Bulk density plays an important role in controlling the quality of diamond and cubic boron nitride, classifying the varieties and grades

Bulk density is important in controlling the quality of diamond powder and cubic boron nitride classifying varieties and grades, and in the manufacture of abrasive tools. For example, because of the high hardness and elastic modulus of diamond, plastic deformation is difficult to occur in the process of making tools. Therefore, choosing the best particle size ratio and improving the bulk density before sintering plays an important role in improving the quality of diamond tools.

The bulk density tester can be used to determine the bulk density of diamonds.

Grinding discs are collectively referred to as tools that perform the functions of grinding and polishing in the machining process. Grinding discs can be divided into natural grinding discs and man-made grinding discs according to the source of their raw materials. With the continuous development of industry and technology, the proportion of natural abrasive discs in the abrasive discs is becoming less and less. The only natural abrasive discs used in the modern machinery industry are oilstone. According to its basic shape and structural characteristics, artificial grinding discs are mainly divided into three categories: consolidated grinding discs, coated grinding discs and grinding pastes.

The successful development of the ceramic bond CBN grinding disc has made CBN grinding discs widely used in grinding processing, especially in forming grinding and mass production. The application of ceramic bond CBN grinding discs in industrially developed countries have expanded from difficult-to-machine materials to general materials, from general grinding (internal and external circular grinding) to forming grinding, centerless grinding, slow-feed grinding, and precision grinding, High-speed grinding, honing and other types of grinding, the application field involves tools, cutting tools, bearings, automobiles, ships, machine tools, aerospace, military and other industrial fields. Although the domestic ceramic bond CBN grinding disc preparation technology is also developing rapidly, the research system is still incomplete due to its late starting, especially in terms of product technology, high-end product performance, and new product development of CBN grinding discs. Considerable gap, most of the high-end products used are imported. With the continuous improvement of modern industrial machining requirements and increasing demand, domestic research on ceramic bond CBN abrasive discs has become more and more important.

Among the CBN grinding discs of various bonding agents, the ceramic bonded CBN grinding discs have sharp cutting, low cutting force, high production efficiency, good shape retention of the wheel, high durability, adjustable air holes, non-clogging during grinding, and It has the advantages of shaping and trimming, high grinding accuracy. And also has the characteristics of low workpiece grinding temperature, can eliminate the surface tensile stress and generate residual compressive stress, which improves the durability of the workpiece by 30% to 50%. When applied to double-end grinding, its high metal removal rate results in fewer burns. At the same time, it can maintain the flatness, parallelism and dimensional accuracy of the workpiece for a long time, improve production efficiency, and reduce overall grinding cost. Therefore, as a kind of high-speed, high-efficiency, high-precision, low-grinding cost, and low environmental pollution high-performance grinding disc products, ceramic bond CBN grinding discs have broad development prospects in the field of double-end grinding.

The PDC cutters are sintered by using the diamond micro-powder and the cemented carbide substrate under ultra-high pressure and high-temperature condition and has high hardness, high wear resistance and thermal conductivity of the diamond, and the strength and impact toughness of the hard alloy. It is the ideal material for cutting tools, drilling bits, and other wear-resistant tools. It is widely used in oil drilling, geological exploration, coal mining drill bit and machining tools.

Drilling and diamond-like cutters: suitable for soft to medium-hard geological drilling, with high impact toughness and thermal stability, heat resistant temperature up to 750 ° C (two minutes), such products are available in flat and various grooves Face combination type, and can be designed according to user needs, groove, grinding, polishing, chamfering, etc., can provide special shape products.

Mechanical tool PDC cutters: suitable for cutting and processing non-metallic, non-ferrous metals and other metals such as high hardness alloys, wood, ceramics, etc., high cutting precision According to users’ needs, the product with high hardness and wear resistance is processed into a rectangular, triangular, fan-shaped shape, etc. It can be used to make wear-resistant parts, drill bits, tips, and drill teeth.

Henan Crownkyn Company introduces international advanced technology, strengthens its own technology development strength training, adopts new high-efficiency catalyst and new technology, and the diamond composite sheet produced has various tooth structure, the interface is firm and uniform, and has high wear resistance. Thermal stability and strong impact toughness.