The application provides in an aspect a process for producing urea in a urea plant comprising a high pressure synthesis section comprising a reactor, wherein the process comprises reacting NH.sub.3 feed and CO.sub.2 feed under urea formation conditions in said reactor to form a urea synthesis solution comprising urea, water, carbamate and ammonia, wherein the process further comprises contacting a carbamate—containing liquid stream with an equipment part of said high pressure synthesis section that is made of a ferritic steel alloy.

An electronic device characterized by including a substrate, a bonding layer provided on the substrate, the bonding layer containing copper in an amount of greater than 0 mass % but 60 mass % or less, the copper having its crystal grain size of 50 nm or less, an electronic component provided on the bonding layer, and a coating film covering a side of the bonding layer, the coating film containing at least one compound selected from copper (I) oxide (Cu.sub.2O) and copper (II) oxide (CuO).

The production of engine parts with a complex geometrical structure. More particularly, a method for producing a complex part, comprising making available a first component, having a thermal expansion coefficient of the first component; a first joining surface; and a first bearing surface; making available a second component, having a thermal expansion coefficient of the second component; a second joining surface; a second bearing surface; and making available a jacket element, having a thermal expansion coefficient of the jacket element; and a jacket-element bearing surface; and heating the first component, the second component and the jacket element from a first temperature to a second temperature in order to carry out a joining process on the first component and the second component. Furthermore, a part, in particular for a gas turbine engine for an aircraft, and to a gas turbine engine of this kind.

A gold powder comprising gold having a purity of 99.9% by mass or more and having an average particle size of 0.01 μm or more and 1.0 μm or less, a content of a chloride ion is 100 ppm or less, and a content of a cyanide ion is 10 ppm or more and 1000 ppm or less. A total of the content of a chloride ion and the content of a cyanide ion is preferably 110 ppm or more and 1000 ppm or less. The gold powder has improved adaptability to various processes including bonding or the like with a content of a chloride ion, that is, an impurity, optimized. A gold paste using this gold powder is suitably used in various uses for bonding such as die bonding of a semiconductor chip, sealing a semiconductor package, and forming an electrode/wire.

Wear resistant articles are described herein which, in some embodiments, mitigate CTE differences between wear resistant components and metallic substrates. In one aspect, an article comprises a layer of sintered cemented carbide bonded to a layer of iron-based alloy via a metal-matrix composite bonding layer, wherein coefficients of thermal expansion (CTE) of the sintered cemented carbide layer, metal matrix composite bonding layer, and iron-based alloy layer satisfy the relation: $x=\frac{\left(.Math.CTE\mathrm{WC}-CTEMMC.Math.\right)}{(.Math.CTE}$

Wear resistant articles are described herein which, in some embodiments, mitigate CTE differences between wear resistant components and metallic substrates. In one aspect, an article comprises a layer of sintered cemented carbide bonded to a layer of iron-based alloy via a metal-matrix composite bonding layer, wherein coefficients of thermal expansion (CTE) of the sintered cemented carbide layer, metal matrix composite bonding layer, and iron-based alloy layer satisfy the relation: $x=\frac{\left(.Math.CTE\mathrm{WC}-CTEMMC.Math.\right)}{(.Math.CTE}$

A heat exchanger is characterized by having two or more fluid flow circuits, each formed by multiple small cross-section “micro-tubes” contained within a surrounding metal structure, or “metal matrix.” Its function is to efficiently transfer heat from one fluid to another in a highly compact assembly. Most any metal or metal alloy can be considered for the micro-tubes. The micro-tubes, while typically arranged in alternating layers of alternating flow circuits, may be organized in any number of arrangements including co-linear and at cross angles to provide for co-flow, counter flow and cross flow. The metal matrix, is provided in one embodiment by a metal or metal alloy powder consolidated in a hot isostatic pressing (HIP) process. This process also joins the tubes together and to the matrix itself, producing a monolithic structure.

A heat exchanger is characterized by having two or more fluid flow circuits, each formed by multiple small cross-section “micro-tubes” contained within a surrounding metal structure, or “metal matrix.” Its function is to efficiently transfer heat from one fluid to another in a highly compact assembly. Most any metal or metal alloy can be considered for the micro-tubes. The micro-tubes, while typically arranged in alternating layers of alternating flow circuits, may be organized in any number of arrangements including co-linear and at cross angles to provide for co-flow, counter flow and cross flow. The metal matrix, is provided in one embodiment by a metal or metal alloy powder consolidated in a hot isostatic pressing (HIP) process. This process also joins the tubes together and to the matrix itself, producing a monolithic structure.

Undercooled liquid metallic core-shell particles, whose core is stable against solidification at ambient conditions, i.e. under near ambient temperature and pressure conditions, are used to join or repair metallic non-particulate components. The undercooled-shell particles in the form of nano-size or micro-size particles comprise an undercooled stable liquid metallic core encapsulated inside an outer shell, which can comprise an oxide or other stabilizer shell typically formed in-situ on the undercooled liquid metallic core. The shell is ruptured to release the liquid phase core material to join or repair a component(s).

The disclosure is directed to wide band-gap semiconductor devices, such as power devices based on silicon carbide or gallium nitride materials. A power device die is attached to a carrier substrate or a base using sintered silver as a die attachment material or layer. The carrier substrate is, in some embodiments, copper plated with silver. The sintered silver die attachment layer is formed by sintering silver nanoparticle paste under a very low temperature, for example, lower than 200° C. and in some embodiments at about 150° C., and with no external pressures applied in the sintering process. The silver nanoparticle is synthesized through a chemical reduction process in an organic solvent. After the reduction process has completed, the organic solvent is removed through evaporation with a flux of inert gas being injected into the solution.