Methods for forming a diamond like carbon layer with desired film density, mechanical strength and optical film properties are provided. In one embodiment, a method of forming a diamond like carbon layer includes generating an electron beam plasma above a surface of a substrate disposed in a processing chamber, and forming a diamond like carbon layer on the surface of the substrate. The diamond like carbon layer is formed by an electron beam plasma process, wherein the diamond like carbon layer serves as a hardmask layer in an etching process in semiconductor applications. The diamond like carbon layer may be formed by bombarding a carbon containing electrode disposed in a processing chamber to generate a secondary electron beam in a gas mixture containing carbon to a surface of a substrate disposed in the processing chamber, and forming a diamond like carbon layer on the surface of the substrate from elements of the gas mixture.

Nano polycrystalline diamond is composed of carbon and a plurality of impurities other than carbon. A concentration of each of the plurality of impurities is not higher than 0.01 mass %, and the nano polycrystalline diamond has a crystal grain size (a maximum length) not greater than 500 nm. The nano polycrystalline diamond can be fabricated by preparing graphite in which a concentration of an impurity is not higher than 0.01 mass % and converting graphite to diamond by applying an ultra-high pressure and a high temperature to graphite.

Disclosed is a method for separating nanodiamond clusters synthesized by a detonation method having a size of 100 nm˜1,000 nm into nanodiamonds of 100 nm or less—more specifically, into uniformly sized nanodiamonds in the range of 5 nm˜50 nm, free of metal and alkaline impurities and ready to quantitatively attach functional groups on the surface of the nanodiamonds for applications such as thin film precursor materials, drug delivery systems and cosmetics compositions.

A composite polycrystal includes: a polycrystalline diamond phase including a plurality of diamond particles; and non-diamond phases composed of non-diamond carbon. The non-diamond phases are distributed in the polycrystalline diamond phase. An average value of projected area equivalent circle diameters of the non-diamond phases is not more than 1000 nm.

A composite polycrystal includes: a polycrystalline diamond phase including a plurality of diamond particles; and non-diamond phases composed of non-diamond carbon. The non-diamond phases are distributed in the polycrystalline diamond phase. An average value of projected area equivalent circle diameters of the non-diamond phases is not more than 1000 nm.

A method of modifying surfaces of diamond particles comprises forming spinodal alloy coatings over discrete diamond particles, thermally treating the spinodal alloy coatings to form modified coatings each independently exhibiting a reactive metal phase and a substantially non-reactive metal phase, and etching surfaces of the discrete diamond particles with at least one reactive metal of the reactive metal phase of the modified coatings. Diamond particles and earth-boring tools are also described.

A method of modifying surfaces of diamond particles comprises forming spinodal alloy coatings over discrete diamond particles, thermally treating the spinodal alloy coatings to form modified coatings each independently exhibiting a reactive metal phase and a substantially non-reactive metal phase, and etching surfaces of the discrete diamond particles with at least one reactive metal of the reactive metal phase of the modified coatings. Diamond particles and earth-boring tools are also described.

Methods of forming composite particles include forming a source material over a plurality of nucleation cores and forming a catalyst material over the source material. Compositions of matter include a plurality of composite particles, each particle of the plurality comprising a plurality of nucleation cores, a source material disposed over the nucleation cores, and a catalyst material disposed over the source material. Methods of forming earth-boring tools include forming a plurality of composite particles, combining the plurality of composite particles with a plurality of grains of hard material, and catalyzing the formation of inter-granular bonds between the composite particles and the grains of hard material to faun a polycrystalline material. The plurality of in situ nucleated grains of hard material and the plurality of grains of hard material may be interspersed and inter-bonded.

A sliding member includes a carbon transfer layer and can superiorly effectively decrease friction and reduce wear. A method produces the sliding member. The sliding member includes a substrate and a carbon transfer layer. The carbon transfer layer is disposed on the surface of the substrate and includes both sp.sup.2 bonded carbon and sp.sup.3 bonded carbon. The carbon transfer layer preferably has a ratio sp.sup.3/(sp.sup.2+sp.sup.3) of the sp.sup.3 bonded carbon to the totality of the sp.sup.2 bonded carbon and the sp.sup.3 bonded carbon of 0.1 or more.

A suspension of nanodiamond aggregates according to the present invention is a suspension of detonation nanodiamond aggregates. The suspension has such a pH and an electric conductivity as to meet one of conditions (1) and (2) as follows. (1) The suspension has a pH of 4 to 7 and an electric conductivity of 50 μS/cm or less per weight percent of the solids concentration of the suspension; and (2) the suspension has a pH of 8 to 10.5 and has an electric conductivity of 300 μS/cm or less per weight percent of the solids concentration of the suspension.