A CVD diamond layer for use as an insert in an abrasive tool characterized by the following features: (i) the layer contains boron dopant atoms in a concentration of at least 0.05 atomic percent; (ii) an average tensile rupture strength of at least 600 MPa with the nucleation phase in tension, and at least 300 MPa with the growth face in tension, both such tensile rupture strengths being measured by a three point bend test on a sample 18 mm long, 2 mm wide and a thickness of 1.4 mm or smaller.
There is disclosed a method for producing a diamond film on a base material by a vapor phase reaction at least with introducing a raw material gas, wherein B(OCH.sub.3).sub.3 gas is added to the raw material gas as a source of boron to be doped, and a diamond film is deposited on the base material by a vapor phase reaction utilizing the mixed raw material gas. There can be provided a method enabling easy and uniform production of a diamond film showing a low electric resistivity value with good reproducibility and few problems concerning handling such as serious bad influence on human bodies and explosiveness during the doping process.
A hard coating that is to be disposed on a surface of a body includes a diamond layer which includes a plurality of diamond grains and is doped with boron, and an outer layer which includes an intermetallic compound and is disposed on the diamond layer by a physical vapor deposition method.
An ultra-hard semiconductive polycrystalline diamond (PCD) material formed with semiconductive diamond particles doped with Li, Be or Al and/or insulative diamond particles having semiconductive surfaces, tools incorporating the same, and methods for forming the same, are provided. The ultra-hard PCD material may be formed using a layer of insulative diamond grit feedstock that includes additives therein, then sintering to convert a plurality of the diamond crystals to include a semiconductive surface. In another embodiment, the ultra-hard PCD material is formed by sintering semiconductive diamond grit feedstock consisting of diamond crystals doped with Li, Al or Be. The ultra-hard semiconductive PCD cutting layer exhibits increased cuttability, especially in EDM and EDG cutting operations.
A method for producing a milling disc with embedded insets of hard metal, ceramics or other similar hard materials. The milling disc has a centrical bore in the base body of the disc. The tips of the insets protrude over the circumference of the disc body. The invention also relates to a milling disc produced according to the method wherein a powdery sintered metal material is filled into the recess of a mold pertaining to a compression molding die, and the mold matches the outer contour of the disc base body. Pre-fabricated insets are inserted into the sintered metal material and are positioned in the mold of the compression molding die. A green compact is subsequently pressed in the compression molding die and then taken out of the compression molding die. The green compact is sintered with the pressed insets and is subjected to hardening and/or surface treatment, if required. According to the milling disc, the resistance of the insets in the disc base body and the properties of the disc base body are improved.
A layer of single crystal boron doped diamond produced by CVD and having a total boron concentration which is uniform. The layer is formed from a single growth sector, or has a thickness exceeding 100 .mu.m, or has a volume exceeding 1 mm.sup.3, or a combination of such characteristics.
