Electrospray application to powder production and surface coating

Easily segregated Cu-15Ni-8Sn alloy bulk material was fabricated using a selective laser melting (SLM) process. The microstructure of SLM-manufactured Cu-15Ni-8Sn alloy was investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Differences in the microstructures and elemental segregation of gas-atomized alloy powder, cast ingots, and SLM-manufactured samples were analyzed. The statistical average grain size of the SLM-manufactured Cu-15Ni-8Sn alloy was 4.03 μm. Microstructures of the SLM-manufactured sample were mainly composed of epitaxially grown slender cellular structures with submicron widths. Microsegregation was detected by TEM, and 80- to 200-nm Sn-enriched precipitates were dispersed between cellullar structures. Many dislocations and dislocation tangles appeared around the precipitates. An EBSD test revealed that most local misorientations within 3 degrees were concentrated in fusion line regions. Compared with cast ingots, the yield strength Rp0.2, ultimate tensile strength Rm, elongation A, and elastic modulus E of the SLM-manufactured sample increased by 67%, 24.6%, 360%, and 7%, respectively. Moreover, the SLM-manufactured Cu-15Ni-8Sn alloy could be directly aged at 350℃ for 12 h, reaching Rm = 991.1 MPa and A =3 %, with no need for solid solution treatment or cold working.

Microstructures and properties of SLM-manufactured Cu-15Ni-8Sn alloy

https://hal.archives-ouvertes.fr/hal-01007131/document

Numerical simulation of grinding induced phase transformation and residual stresses in AISI-52100 steel

The ultra-fast cooling technology of large section bars and the microstructure for different cooling patterns were studied by optical microscope, transmission electron microscope and energy spectrometer. The results indicated that the large section bars were passed through the zone of secondary carbide precipitation quickly by ultra-fast cooling technology (UFC) at instantaneous cooling rate of about 200°C/s and the finishing cooling temperature was higher than M s . The lamellar spacing of pearlite decreased and the microhardness increased with decreasing the rereddening temperature. The precipitation of network carbide was restrained when re-reddening temperature was 690°C. And fine laminated pearlite was obtained through transformation of pseudopearlition that induced the reduction of the diameter of pearlite grain and refinement of the lamellar spacing of pearlite, so ideal microstructures of promoting spheroidizing annealing were obtained.

Effect of Ultra-Fast Cooling on Microstructure of Large Section Bars of Bearing Steel

Microstructure and age characterization of Cu―15Ni―8Sn alloy coatings by laser cladding

Research in spray forming technology and its applications in metallurgy

Microstructure of the spray formed GCr15 steel was observed by optical microscopy and transmission electron microscopy, showing fine pearlite with the interspacing of 85 nm in as-sprayed samples and martensite of the width of 0.35 μm in oil-quenched samples. Two formulae correlating the hardness with the interspacing of the pearlite and the width of the martensite, respectively were derived on the basis of the Hall–Petch relation. A comparison of continuous cooling transformation thermograms between the as-sprayed and the as-received GCr15 steel revealed the differences of Ms temperature and transformation temperature from pearlite to austenite, which were quantitatively investigated and found that it originated from different carbide distribution and different carbon content in the matrix of steel.

Microstructure and continuous cooling transformation thermograms of spray formed GCr15 steel

Microstructure and properties of spray formed Cr12MoV steel for rolls

Although the rational synthesis of catalysts with strong oxide-support interactions to modulate the geometric and electronic structures and achieve unusual catalytic performance is challenging in heterogeneous catalysis, it is in significant demand for the efficient and sustainable transformation of chemicals. Here, we report the synthesis and performance of a ceria-supported two-dimensional manganese oxide catalyst with strong metal oxide-support interactions, which help to produce well-dispersed and amorphous MnOx layers on the CeO2 matrix (MnOx/CeO2). This catalyst readily reacts with molecular oxygen to give a high capacity of active oxygen species, owing to the interfacial effect. The C-H bonds are adsorbed and activated by these active interfacial oxygen species, leading to high activities and selectivities in the industrially important C-H bond activation reactions, such as the oxidation of hydrocarbons to alcohols and ketones with molecular oxygen under solvent- and initiator-free conditions at mild temperature. The performance of the MnOx/CeO2 catalyst is greater than that of noble metal and highly efficient Mn-Ce solid-solution catalysts. More importantly, the catalyst is stable and exhibits constant reactivity in continuous recycling tests. These results are important for the design of highly efficient catalysts for the selective oxidation of hydrocarbons.

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Jing Guo Zhang

Papers

Research in spray forming technology and its applications in metallurgy

Microstructure and continuous cooling transformation thermograms of spray formed GCr15 steel

Microstructure and properties of spray formed Cr12MoV steel for rolls

Two-dimentional manganese oxide on ceria for the catalytic partial oxidation of hydrocarbons

Selective conversion of acetone to mesitylene over tantalum phosphate catalysts.