Theunique surface characteristics of nanopowders deduce their application inelectrochemical andchemicalcoatings, pastes, and suspensions; as additives in polymeric, ceramic, andindustrial rubber goods and glues; as adsorbents and catalysts, in filters andmembranes. Nanodiamond powder of detonation synthesis are applied intechnologies of hard electrochemical compound coatings of diamond tools149. Inparticular, a nanodiamond additive changes the structure of nickel coatingswith the formation of nickel dendrites radiating outward from dispersedparticles and increases the microhardness of coatings by a factor of 1.9 andtheir wear resistance by 3–4 times. Such compoundscoatingssignificantly enhance the quality of galvanic tools with different types ofdimension and functions (grinding wheels, core drills, faceplates, etc.) andharden the work surfaces of flying grippers for printing machines, sleeves ofinternal-combustion engines, etc150.Techniques have been advanced for metalizing static-synthesis diamond powdersby composite chemical coatings with nanodiamond additives and for metalizingnanodiamond itself by nickel to produce diamond-carrying cells 0.35–1.
8 µm insize. The application of composites based on metallized nanodiamond to formfaceting disks for processing jewels at the Izumrud State Company increased thewear resistance, elasticity, rollability, and cutting ability of the disks by afactor of 1.5–1.8151,152. Studies about the catalytic andadsorption properties of nanodiamond indicate that adsorption centres on the particle surface aresimultaneously catalytic centres.
Thiswas shown that electrochemical treatment of the particle surface makes itpossible to saturate it with atomic oxygen, thereby significantly enhancingcatalytic oxidation of carbon monoxide into dioxide27,153. Sincenanodiamonds have demonstrate to be promising catalysts of oxygen electrodes infuel cells, those studies were further developed. Techniques have beendeveloped for sintering nanopowders and for applying them as a structuring additives in the manufacturing of densepolycrystals from static synthesis of diamonds.
One of the most interestingresults is the technology of polycrystalline micropowderswhose porous particles have various nanostructures154. Suchpowders are manufactured by crushing diamond nanopowder sinters produced understatic conditions in the region of stability of the diamond phase155. Theminimum pore size of powder particles, estimated from the characteristics ofnitrogen adsorption, is 1.2 nm. The particles of powder of granularity 1/0 have pores sizerange from 1.2 to 2.
5 nm. As the granularity increases, the largest pore sizeincreases to ~10 nm. The important advantages of polycrystalline powders islarge specific surface area (~140 m2 g–1), which is close to that of theinitial nanopowder (~170 m2 g–1), and their high adsorption activity (above 250J g–1)156. Theseproperties make it feasible to use polycrystalline powders as adsorbents andcatalysts; therefore, the search for their most efficient fields of applicationis carried out in this direction. As for the polishing ability of powders, theycan be used for the processing of both hard and soft materials.
Through tuning chemical, optical, electric, and magneticproperties of materials, nanotechnology offers medicine as a strong progressivetreatment for patients. For example, it may help in reducing serious adverseeffects of chemotherapy through the targeted delivery of therapeutics at themalfunctioning site. Carbon nanomaterials are mainly attractive for biomedicalapplications because carbon is the main constituent of all living organisms onEarth, including the human body. Since the development of the era of nanotechnology, carbon-basednanomaterials such as fullerenes, carbon nanotubes, graphene, and nanodiamondhave been in the focus of researchers to develop the theranostic platforms157. Amongdifferent carbon nanomaterials, nanodiamondparticles (ND) are excellent due to their biocompatibility and low toxicity, chemicalinertness of diamond core with highly tailorable and fully accessible surface,exposing a number of functional groups that can be used to modify their affinityto different environments, non-covalent or covalent attachment of drugs orbiomolecules, as well as incorporation into composites and hybrid materials forbiomedical applications158.
Some ofthese nanodiamonds bear fluorescent centres in their cores gives the opportunities for invitro and in vivo imaging. Others have a very smallsize (5 nm or less indiameter) being potentially able to penetratethe smallest pores in the body, for example, in the nuclear membrane (nucleolemma), or kidney filtrationsystem. With all these unique properties combined in one particle, nanodiamonds outperform other nanoparticles that providesome of these properties but not all. These advantages of nanodiamonds don not matchedby any other carbon or non-carbon nanomaterial are already important enough to providenanodiamonds as the superior nanomaterial for different application (Figure6)159. And yet,nanodiamonds offer more benefits: it can be relatively, easily andinexpensively synthesized by detonation on a large industrial scale and isalready commercially available at affordable price. All these factors grant thegrowing interest in using the hardest material (diamond) atits nanoscale form to fight with some of the hardest problemsfaced by human society160.