A method of using a ferrous structural component is described. The method comprises integrating a ferrous structural component into process equipment, where the ferrous structural component comprises an iron alloy body with a modified surface including an aluminized surface layer that comprises one or more iron aluminides. The modified surface of the iron alloy body is exposed to an oxidative environment, thereby forming, as part of the modified surface, a passivating layer comprising aluminum oxide on the aluminized surface layer. The modified surface is also exposed to a process fluid. The exposure to the oxidative environment occurs prior to and/or upon exposure of the modified surface to the process fluid. Due to protection afforded by the passivating layer, the modified surface resists fouling and corrosion while exposed to the process fluid, as exhibited by a substantial absence of carbonaceous deposits on the iron alloy body.

A coated cutting tool includes a substrate and a coating. The coating has an inner layer of 4-14 m thick Ti.sub.1-xAl.sub.xN, an intermediate layer of 0.05-1 m TiCN and at least one outer layer of 1-9 m -Al.sub.2O.sub.3. The -Al.sub.2O.sub.3 layer exhibits an X-ray diffraction pattern, as measured using CuK radiation and theta-2theta scan. A texture coefficient TC(hkl) is defined according to Harris formula, wherein the (hkl) reflections used are (0 2 4), (1 1 6), (3 0 0) and (0 0 12), I(hkl)=measured intensity (peak intensity) of the (hkl) reflection, 10(hkl)=standard intensity according to ICDD's PDF-card No. 00-042-1468, n=number of reflections used in the calculation, and 3<TC(0 0 12)<4.

A diamond coated tool includes a base material and a diamond layer provided on the base material. The diamond layer has a boron content of 1?10.sup.3 ppma or more and 1?10.sup.6 ppma or less and an oxygen content of 1?10.sup.2 ppma or more and 1?10.sup.5 ppma or less in a first region surrounded by a surface of the diamond layer and a first imaginary plane located at a distance of 1 ?m from the surface in a thickness direction.

A coated tool includes a base and a coating layer located on the base. The coating layer includes a first layer having a thickness of 1 m or more located near the base, and a second layer including Al.sub.2O.sub.3 particles which is in contact with the first layer and is located more away from the base than the first layer. A difference (A2A1) between an erosion ratio A2 in the second layer and an erosion ratio A1 in the first layer is 0.60 to 0.30 m/g. The erosion ratio is obtained by collision of a liquid A in which 3 mass % of spherical Al.sub.2O.sub.3 particles having a mean particle diameter of 1.1-1.3 m is dispersed in pure water. A cutting tool includes a holder which includes a pocket, and the coated tool located in the pocket.

A sealing process includes applying a first reactant to a substrate having a porous structure, the first reactant comprising a chromium (III) precursor and a transition metal precursor and applying a second reactant to the first reactant, the second reactant comprising a rare earth element precursor and an alkaline earth element precursor to form reservoirs of trivalent chromium in pore space of the porous structure, and a physical barrier over the substrate and the reservoirs.

The present invention relates to a method of case hardening a Group IV metal or a Group IV metal alloy and to components hardened in the method. The method comprising the steps of: providing a workpiece of a Group IV metal or a Group IV metal alloy, the workpiece being in its final shape; nitriding the workpiece in a nitriding atmosphere comprising NHs as a nitriding species at a first temperature in the range of 450? C. to 750? C. for a nitriding duration of at least 16 hours to provide a hydrogen containing diffusion zone; removing hydrogen from the hydrogen containing diffusion zone at a second temperature of up to 750? C. and a partial pressure of H.sub.2 of up to 10.sup.?4 mbar over a hydrogen removal duration of at least 4 hours to provide a hydrogen depleted diffusion zone. The method and the component are useful for implants, in particular dental implants.

An example article includes a substrate and a barrier coating on the substrate. The barrier coating includes a matrix including a rare-earth disilicate extending from an inner interface facing the substrate to an outer surface opposite the inner interface. The barrier coating includes a graded volumetric distribution of rare-earth oxide rich (REO-rich) phase regions in the matrix along a direction from the inner interface to the outer surface. The graded volumetric distribution defines a first volumetric density of the REO-rich phase regions at a first region of the matrix adjacent the outer surface. The graded volumetric distribution defines a second volumetric density of the REO-rich phase regions at a second region of the matrix adjacent the inner surface. The second volumetric density is different from the first volumetric density. An example technique includes forming the barrier coating on the substrate of a component.

Provided is a piston ring having excellent low-friction properties and abrasion resistance manufactured without the need for precision control using an ordinary film formation device that does not have a special function. A piston ring obtained by coating an amorphous carbon film on the surface of a ring-shaped substrate, the piston ring being configured so that the amorphous carbon film is formed by CVD, an increase region, in which the ratio sp.sup.2/sp.sup.3 of the sp.sup.2 bond to the sp.sup.3 bond continuously increases from the substrate surface toward the film surface, and a decrease region, in which the ratio sp.sup.2/sp.sup.3 continuously decreases, are formed in alternating fashion, a soft film in which the ratio sp.sup.2/sp.sup.3 is low and a hard film in which the ratio sp.sup.2/sp.sup.3 is high are formed so as to be layered in alternating fashion by continuous variation of the ratio sp.sup.2/sp.sup.3 in the boundary between the increase region and the decrease region, and the decrease regions are formed in equal number to or with one region less than the number of increase regions.

An abrasion-resistant and friction-reduced coating for metal components is provided. The coating includes an inner layer, an intermediate layer and an outer layer. The inner layer is intended to be applied to the metal component and has at least one layer selected from: a metal layer, a metal-carbide layer, a metal-nitride layer, a metalcarbide- nitride layer and a metal-containing hydrocarbon layer. The intermediate layer includes at least one layer of amorphous carbon and the outer layer includes a WC:H layer or a a-C:H* layer. A maximum layer thickness of the coating is at most 5 m. The coating is suitable in particular as a piston coating for use in internal combustion engines.

Method of treating a workpiece comprising a titanium metal, wherein a titanium metal surface layer of the workpiece is converted to titanium nitrides. The method comprises the following steps; a) heating the workpiece to an initial nitriding temperature (T.sub.n1) and b) subjecting said workpiece to one or more nitriding temperatures (T.sub.n1, T.sub.n2) for predetermined time(s) in a nitrogen containing gas under high pressure at hot isostatic pressing (HIP) conditions for converting the titanium metal surface layer to a first layer portion consisting of titanium nitrides and a second layer portion comprising a nitrogen gradient in the titanium metal. The method further comprises c) quenching the workpiece in the nitrogen containing gas under high pressure at hot isostatic pressing (HIP) conditions, in order to strengthen the titanium metal below the in step b) formed first nitride layer portion.