Methods of forming an environmental barrier coating are disclosed. A method includes disposing a powder-based coating on a substrate, heat-treating the powder-based coating at a temperature greater than 800° C. and less than 1200° C. to form a porous coating that includes surface-connected pores, infiltrating at least some of the surface-connected pores of the porous coating with an infiltrant material to form an infiltrated coating, and sintering the infiltrated coating at a temperature greater than 1200° C. and less than 1500° C. to form the environmental barrier coating on the substrate.

Novel nanoparticle-coated multilayer shell microstructures are disclosed herein. Some variations of the invention provide a material comprising a plurality of hollow microstructures characterized by an average shortest diameter from about 5 microns to about 1 millimeter, wherein each of the microstructures comprises multiple shells, including at least an inner shell and an outmost shell, with a combined thickness that is less than one-tenth of the average shortest diameter. The inner shell and the outmost shell have different composition. The outmost shell comprises nanoparticles sized between about 10 nanometers to about 500 nanometers, and the nanoparticles each contain an oxide and/or are surrounded by an oxide layer having a layer thickness of at least 1 nanometer. Several microstructure configurations are illustrated in the drawings.

Novel nanoparticle-coated multilayer shell microstructures are disclosed herein. Some variations of the invention provide a material comprising a plurality of hollow microstructures characterized by an average shortest diameter from about 5 microns to about 1 millimeter, wherein each of the microstructures comprises multiple shells, including at least an inner shell and an outmost shell, with a combined thickness that is less than one-tenth of the average shortest diameter. The inner shell and the outmost shell have different composition. The outmost shell comprises nanoparticles sized between about 10 nanometers to about 500 nanometers, and the nanoparticles each contain an oxide and/or are surrounded by an oxide layer having a layer thickness of at least 1 nanometer. Several microstructure configurations are illustrated in the drawings.

A method of fabricating a centralizer for a tubular body in a wellbore is provided herein. The method includes providing a centralizer, wherein the centralizer include an elongated body having an inner surface and an outer surface, and wherein the inner surface defines a bore there through. The bore is dimensioned to slidingly receive a tubular body. The method also includes applying a first low-coefficient of friction treatment to the inner surface and the outer surface using a ferritic nitro-carburizing process. The method further includes depositing a second low-coefficient of friction treatment onto at least the inner surface. The coatings are designed to provide a reduced coefficient of friction on the surfaces.

A method of fabricating a centralizer for a tubular body in a wellbore is provided herein. The method includes providing a centralizer, wherein the centralizer include an elongated body having an inner surface and an outer surface, and wherein the inner surface defines a bore there through. The bore is dimensioned to slidingly receive a tubular body. The method also includes applying a first low-coefficient of friction treatment to the inner surface and the outer surface using a ferritic nitro-carburizing process. The method further includes depositing a second low-coefficient of friction treatment onto at least the inner surface. The coatings are designed to provide a reduced coefficient of friction on the surfaces.

Provided is a steel for nitrocarburizing that ensures mechanical workability before nitrocarburizing treatment. A steel for nitrocarburizing comprises: a chemical composition containing, in mass %, C: ≥0.02% and <0.15%, Si: ≤0.30%, Mn: 1.5-2.5%, P: ≤0.025%, S: ≤0.06%, Cr: 0.5-2.0%, Mo: 0.005-0.2%, V: 0.02-0.20%, Nb: 0.003-0.20%, Al: >0.020% and ≤1.0%, Ti: >0.0050% and ≤0.015%, N: ≤0.0200%, Sb: 0.0030-0.010%, with a balance being Fe and inevitable impurities, satisfying Expression (1) or (2); and a steel microstructure where an area ratio of bainite phase is >50%, a prior austenite grain size is ≤100 μm, ≥300/μm.sup.2 Ti precipitates with an equivalent circular particle size of ≤30 nm disperse, Sb segregates to prior austenite grain boundaries.

Provided is a steel for nitrocarburizing that ensures mechanical workability before nitrocarburizing treatment. A steel for nitrocarburizing comprises: a chemical composition containing, in mass %, C: ≥0.02% and <0.15%, Si: ≤0.30%, Mn: 1.5-2.5%, P: ≤0.025%, S: ≤0.06%, Cr: 0.5-2.0%, Mo: 0.005-0.2%, V: 0.02-0.20%, Nb: 0.003-0.20%, Al: >0.020% and ≤1.0%, Ti: >0.0050% and ≤0.015%, N: ≤0.0200%, Sb: 0.0030-0.010%, with a balance being Fe and inevitable impurities, satisfying Expression (1) or (2); and a steel microstructure where an area ratio of bainite phase is >50%, a prior austenite grain size is ≤100 μm, ≥300/μm.sup.2 Ti precipitates with an equivalent circular particle size of ≤30 nm disperse, Sb segregates to prior austenite grain boundaries.

At least a part of a burner for a catalytic reactor is coated with a silicate based nickel aluminide slurry diffusion coating.

At least a part of a burner for a catalytic reactor is coated with a silicate based nickel aluminide slurry diffusion coating.

A nickel-based alloy is coated with a silicate based nickel aluminide slurry diffusion coating.