Nano Diamond Black Powder (Monocrystalline Polycrystalline Blend)

Nano Diamond Black Powder (Monocrystalline Polycrystalline Blend)

Nano diamond applications in the mechanical industry

（1）Nano Diamond Composite Coating

Nano Diamond Composite Coating Technology is one of the key technologies for product manufacturing. Through surface coating, the surface of the product can be protected by a protective layer of controlled composition and organization, which significantly improves the service life and reliability of the product. For example: marine platforms, large-scale open pit mining, metallurgical and petrochemical production equipment in harsh environments, the use of long-lasting composite protection can produce internal corrosion in the use of the period of 5 to 10 years; the machinery industry uses a large number of widely used cutting tools, molds, pumps, bearings, valves, the use of the surface strengthening, the service life can be increased by 3 to 5 times.

Nano Diamond Composite Coating Technology is an effective means to improve quality, efficiency, energy saving, material saving, environmental protection and economic benefits. Statistics show that machinery manufacturing in about 1/3 of the energy directly or indirectly consumed in wear and tear, abrasion caused by loss, the world’s steel production of 1/10 loss of rust and other corrosion, corrosion and abrasion to the national economy caused by the staggering losses, according to the United Kingdom, the United States and other countries to investigate the national economy, 2% to 4% of the total output value of the loss of loss due to corrosion, the country’s annual loss due to corrosion caused by at least more than 40 billion yuan, according to the investigation of our country’s 27 provinces and municipalities of about 400 mechanical industrial enterprises, the loss of 11.6 billion yuan a year due to corrosion. It is understood that the world’s annual metal corrosion loss of about 150 billion U.S. dollars, China’s annual loss of 150 billion yuan, and metal plating is one of the ways to solve this technical problem.

In recent years, the high hardness and corrosion resistance of diamonds for composite plating have attracted increasing attention. However, since the general diamond particles are micron or submicron, the particles are relatively coarse, the obtained coating organization is difficult to meet the requirements of precision instruments, high gloss surface, fine machining and higher wear resistance. With the rapid development of nanocrystalline diamond production technology, especially the emergence of 2-12 nm diamond, the use of nanocrystalline diamond to form a composite layer is expected to make up for this deficiency. Brush plating technology is a new type of surface modification technology developed on the basis of electroplating technology in recent years, which can solve the problems of mechanical parts repair that are difficult to be solved by other technologies. The Open Research Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, in cooperation with the Department of Materials, Lanzhou University, investigated the tribological properties of the composite nickel-brush coating containing nanomaterials, which showed that the coating has excellent friction and abrasion resistance, and its friction and abrasion resistance increases with the increase of the content of nano diamond black powder in the test range.

At present, our country produces more than 3 billion cylinders annually, which are mainly used in automobile, motorcycle, home appliance, mining machinery, textile machinery, shipbuilding and precision machine tools, instrumentation, military and other industries, and urgently need to upgrade the nanocomposite plating technology. In addition, China’s molds and plastics, glass decorative plating market is huge, according to rough calculations, if the plating surface reaches 3.0 × 108 m2, the thickness of the plating layer according to the calculation of 5 μm, each square meter needs to use nano diamonds 0.2 g, then nano diamonds required for nano diamond-metal composite plating additives will amount to 6.0 × 105 kg. Nano diamond composite plating has a bright future.

Adopting effective means of protection can reduce corrosion loss by at least 15%~35% and wear loss by about 1/3. In addition, because the surface coating is very thin, the surface coating and modification often use very little material to significantly improve the performance of corrosion and abrasion resistance, etc., which has obvious economic benefits in saving valuable materials and reducing manufacturing costs. For example, for worn out molds, crankshafts, guides, cylinder liners, cases, shafts, bearing seats, bucket teeth, linings and other parts, as well as crawler vehicle parts, the use of brush plating technology to carry out normal maintenance work, with great economic benefits.

After studying the tribological properties of nano diamond composite chromium plating layer, it was found that the addition of nano diamond powder to the composite plating layer can form a homogeneous and dense composite plating layer. The addition of nano diamond powder can refine the grain size of the layer, which plays the role of diffusion strengthening and improves the hardness of the composite chromium plating layer. Under oil lubrication conditions, the addition of nano diamond powders significantly improves the abrasion resistance of the plating layer, and the best results are obtained at a layer thickness of 27 μm, with a 12-fold increase in abrasion resistance compared to a pure chromium plating layer.

Nano composite plating is a deposition technique in which insoluble nano diamond particles are added to the plating solution to form a homogeneous suspension, and the solid particles are co-deposited with metal ions to obtain a composite plating layer. The nanoparticles are fully dispersed by suspension technology, and the nanocrystalline diamond composite layer obtained has excellent properties such as high abrasion resistance and friction reduction. The hardness of nanocomposite diamond plating can reach HV700~1100, and the abrasion resistance is superior to that of Cr15, normal nickel plating and micron diamond composite plating. The coefficient of friction is only one-third of that of conventional coatings. It has a unique self-lubricating effect, and the life of abrasion resistance can be increased by 2-5 times. It can be widely used in the surface treatment of precision wear-resistant parts in various industries, replacing the original chrome plating, nickel plating and other processes. The application effects are shown in Tables 1-3.

表1 Experimental Results of Chromium Coated Drill Bits Containing Nano Diamonds

表2 Experimental Results of Chromium-Diamond Coated Compression Molds

Relative life compared to nitriding, carburizing, Chromium plating and special steel tools.

表3 Chromium Diamond Coating Stamping Tools(Negative mold, Positive mold)

Experimental results during sheet stamping

（2）Lubricants containing nano diamonds

Nano diamond in the lubricating oil in the strange effect than many people expected, it is not only used in the production of engine oil, but also can be used to make worm gear oil, gear oil, hydraulic oil, vacuum pump oil, high-speed machinery oil, machine tool oil and so on. Recent studies have shown that the addition of nanocrystalline diamonds to lubricating oils has shown the following advantages:

(1) Improve the quality and competitiveness of products; increase the working life of transportation tools and devices; save lubricant materials.

(2) Friction momentum is reduced by 20% to 40%.

(3) Friction surface wear is reduced by 30% to 40%.

(4) Rapid break-in of the friction pair.

Unit consumption of nano diamond: 0.01～0.20 kg in 1000 kg of lubricating oil. In 2002, China consumed about 4.0×106 tons of lubricating oil, with sales amounting to tens of billions of dollars and increasing at a rate of 10% per year. Utilizing the characteristics of nano diamond, the research and development of high-efficiency special-purpose internal combustion engine break-in oil has been tested by laboratory physical and chemical indexes and engine bench test, which proves that it can significantly shorten the time, improve the quality of break-in, improve the wear-resisting performance of engine mating surfaces, and lengthen the service life of the engine, realizing the organic combination of engine break-in and surface modification.

Currently, metal lubricants are commonly used to pre-grind the surface of the friction sub-surface to impart the anti-wear properties of the metal lubricant to the surface of the friction sub-surface. Experimental data proved that metal lubricants containing nanocrystalline diamond powder can reduce wear by 1.7 to 2.0 times, shorten break-in time by 1.5 to 2.4 times, and reduce friction coefficient by 1.25 to 2.0 times.

（3）New wear-resistant materials containing nano diamonds

In 1992, Yashchenko in the United States with powder metallurgy into a new anti-wear materials, this material is the copper-zinc and copper-tin powder and nano-amalgamite powder mixed with a certain proportion of compaction, and then sintered in hydrogen to produce. This new material can be used in the manufacture of internal combustion engine cylinder liner and other transmission machinery bushings, can also be used in the manufacture of sliding bearings, etc. Because this new material contains a small coefficient of friction, high thermal conductivity of the nano-grade diamond powder, so it has a high resistance to scratches and wear resistance.

The metal repair agent made of nano diamond has been tested to increase tensile strength by 71.98%, torsional strength by 19.75%, and abrasion resistance by 154.82%.

Foreign reports mention that nanomaterials can be used in aircraft and ships fuselage, wings and hull surface of the organic silicon coating, can enhance the coating of corrosion, frost, temperature, aging resistance, improve the elasticity, fracture strength and tear strength, so that the service life of the surface coating to increase the 1.5 ~ 2.0 times, and the cost of the increase of only 1% ~ 2%.

Nano Diamond Composite Materials

Fluorine rubber and butadiene rubber are modified by using purified or post-blast synthesized products (black and gray nano diamond). Research has shown that although explosive black powder can improve the hardness of rubber, but the tensile strength and elongation at break instead of decreasing. The addition of nano-diamond gray powder to fluoroelastomer increases the overall performance index of the rubber. This is because Nano Diamond Grey Powder contains functional groups such as hydroxyl group, carboxyl group, methyl group, etc., which enhances the activity of bonding with polymers, and thus improves the performance indexes such as tensile property, hardness and abrasion resistance of rubbers.

Research by Russian scholars has shown that the addition of nanodiamonds to fluorine films increases the resistance to abrasion by a factor of one. After adding nanodiamonds to polyisoprene rubber used in tires, the abrasion resistance, elongation, slowing down the aging process and other properties increased by 1.3 to 1.7 times, and the high-temperature tear resistance was significantly improved, and the burst strength of tires (from 53 MPa to 154 MPa) was increased. Silicone rubber filled with black powder, so that the fracture strength in the absolute length increased by about three times from 53MPa to 154MPa, the integrated elastic strength increased by 3 to 5 times, and its critical and maximum modulus of elasticity corresponds to the black powder content of about 0.6% by weight; in the fluorine rubber composition filled with black powder, so that abrasion wear resistance increased by 1.5 to 2 times, similar to the polyisoprene rubber.

At present, most of the studies have focused on the use of nanocrystalline diamond or black powder as fillers in rubber or plastic products with strong functionality, and they are all low-filled, with the amount of addition generally less than 1% Replacing 1-3% (w/w) of conventional carbon fillers by the same weight of nano-amalgamated black powder in rubber processing can extend the service life (mileage) of non-polar isoprene rubber automobile tires by 30%, and increase the service life of rubber workpieces such as bushings by 30-100%. At the same time, the addition of nanocrystalline diamond reduces the porosity, the power required for mixing is reduced by 5-7%, and air bubbles, debris, and adhesion on the surface can be reduced, making it easier to demold.

The effects of modification of plastics by nano diamond black powder and nano diamond grey powder are as follows:

（1）The thermal oxidation properties of the unmodified black powder composites in air were improved. The thermal decomposition temperatures of the HDPE and LLDPE composites filled with 05% black powder were increased by 9°C and 5°C, respectively, compared with those of the pure matrix.

（2）The tensile strength of the composites obtained by filling the polymers with unmodified black powder did not change much, but decreased at higher filling amounts. Tensile strength was improved by filling with modified black powder. The impact strength of the filled composite decreases regardless of whether the black powder is unmodified or modified. The friction and wear properties of composite materials increase with the amount of black powder In summary, the optimal filling amount of black powder for HDPE is considered to be 0.5%, and the optimal filling amount for LLDPE is considered to be in the range of 0.3% to 0.5%.

（3）Filled with .05% black powder HDPE composite material, in the test load is lower than 2kg, friction wear performance by the load of the influence of the change is not big, more than 2k5g, friction wear performance significantly worse; Filled with 0.5% black powder LDLPE composite material, in the test load is lower than 10kg, friction wear performance by the load of the influence is not big, more than 10kg when friction wear performance is significantly worse. The friction wear performance is not much affected by the test load when the test load is lower than 10kg, but the friction wear performance deteriorates significantly when it exceeds 10kg.

（4）The dispersion and compatibility of unmodified nano diamond black powder or nano diamond gray powder in PP are better. The addition of nano diamond black powder or nano diamond gray powder increased the crystallinity of a-state crystals of PP, but did not lead to the formation of other crystal types. PP with 0.06% nano-diamond black powder or 0.06% nano-diamond grey powder increased the crystallinity by T16.74% and 25.83%, respectively, compared with the substrate. The tensile strength of PP-based composites increases with increasing filler content, while the impact strength decreases. Due to the dual effects of free radicals on the crystalline region of PP matrix and on the amorphous region, the impact strength of PP-based composites fluctuates with the increase of nano-particle content, and the maximum value occurs at about 0.06% of the filling amount. The improvement effect of nano diamond gray powder on PP properties is better than that of nano diamond black powder.

（5）Adding Nano Diamond Grey Powder to epoxy resin adhesive increases the strength of anti-breakage by 2-2.5 times.

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