Platinum/rhodium Alloy Bushing for Drawing Glass Fibers in Centrifugal-spinneret-blow Process

In this paper,glass fibers were prepared by centrifugal-spinneret-blow(CSB) process.The molten glass got different flow rate from 390 kg/h to 270 kg/h by adjusting the electric current of platinum/10 rhodium alloy bushing.The diameter and microstructure of glass fibers have been investigated by scanning electron microscopy(SEM) and vertical optical microscope(VOM).The results indicated that the flow rate of molten glass was proportional to the diameter of glass fibers when the molten glass got main flow rate of 330 kg/h.The lower the flow rate was,the finer the average diameter was.

Small amount but big impact:Trace oxygen interstitially inserted PtCu alloys by microalloying for efficient oxygen reduction catalysis

The introduction of small size non-metal elements(e.g.,oxygen)into solid solution alloys may be a promising strategy for fabricating efficient Pt-based catalysts with high activity and stability toward oxygen reduction reaction(ORR).Herein,oxygen interstitially inserted PtCu(O-PtCu)alloys are firstly designed by an oxygen-microalloying strategy,through ultraviolet(UV)irradiation-assisted galvanic replacement in an aqueous solution containing H_(2)PtCl_(6)and Cu_(2)O nanowires as sacrificial templates.The obtained O-PtCu alloys feature a typical face-centered cubic(FCC)structure with majority Pt,Cu atoms as building bricks and trace interstitial oxygen(1.65 wt.%)existed in the octahedral sites surrounding Cu atoms,leading to a short-range disordered structure.The alloy reaches a recorded half-wave potential of 0.96 V(vs.reversible hydrogen electrode(RHE))and mass activity of 0.48 A·mgPt^(−1),much higher than those of commercial Pt/C.During the accelerated degradation test(ADT),the mass activity lost only 4.2%after 10k cycles,while the commercial Pt/C lost 66.7%under the same conditions.Compared with pure Pt and undoped PtCu alloy,the remarkably improved performance can be attributed to the lattice distortion and energy band reconstruction caused by the interstitial oxygen atoms in form of Cu–O bonds.Moreover,the stable Cu–O bonds delay the possible place exchange between surface Pt atoms and surface-adsorbed oxygen species,thereby hindering Pt dissolution,providing a new paradigm to address Pt degradation issue.Therefore,the introduction of interstitial oxygen into Pt-based alloys may be a facile and smart strategy for the development of advanced Pt-based alloys electrocatalysts.

Preparation and catalytic activity of CO-resistant catalyst core-shell Au@Pt/C for methanol oxidation

Au@Pt core-shell nanoparticles were successfully synthesized by a successive reduction method and then assembled on Vulcan XC-72 carbon surface. Furthermore, its composition, morphology, structure, and activity towards methanol oxidation were characterized by UV-vis spectrometry, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Results reveal that Au@Pt/C catalyst has better activity towards methanol oxidation than the pure platinum prepared under the same conditions. When the atomic ratio of Au to Pt in the prepared Au@Pt/C catalyst is 1:2, this catalyst exhibits best electrocatalytic activity towards methanol oxidation in acidic media, and the peak current density on this catalyst is ~2.0 times higher than that on Pt/C catalyst. The better catalytic activity of Au@Pt/C results from its better resistance to toxic CO than Pt/C because the CO oxidation on Au@Pt/C is 60 mV more negative than the case on Pt/C. © The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2012.

Study of the Structure of Oxide Interface in the Pt-Rh Alloy by AP-FIM

This paper reports the study of structure of oxide interface in Pt-Rh alloy by atom probe field ion microscope (AP-FIM) which is well suited for the study of atom distribution with atomic scale at the surface and interface of alloy. AP depth profiles show that oxide interface exist in the Pt-Rh alloy which consists of PtO, RhO, PtO2 and RhO2. The mechanism of oxidation of the alloy is considered as that first oxygen molecules adsorbed on-to the surface of alloy then dissociate into oxygen atoms (O2&rarr2O). Consequently oxygen atoms diffuse into interior through grain boundary forming oxide (M+O&rarrMO). When the concentration of oxygen continuously increases the dioxide (MO+O&rarrMO2) forms.

Stacking fault,dislocation dissociation,and twinning in Pt_(3) Hf compounds:a DFT study

The Pt3Hf compound plays a decisive role in strengthening Pt-Hf alloy systems.Evaluating the stacking fault,dislocation dissociation,and twinning mechanisms in Pt3Hf is the first step in understanding its plastic behavior.In this work,the generalized stacking fault energies(GSFE),including the complex stacking fault(CSF),the superlattice intrinsic stacking fault(SISF),and the antiphase boundary(APB) energies,are calculated using firstprinciples calculations.The dislocation dissociation,deformation twinning,and yield behavior of Pt3Hf are discussed based on GSFE after their incorporation into the Peierls-Nabarro model.We found that the unstable stacking fault energy(γus) of(111)APB is lower than that of SISF and(010) APB,implying that the energy barrier and critical stress required for(111)APB generation are lower than those required for(010)APB formation.This result indicates that the a<110> superdislocation will dissociate into two collinear a/2<110> superpartial dislocations.The a/2<110> dislocation could further dissociate into a a/6<112> Shockley dislocation and a a/3<211> superShockley dislocation connected by a SISF,which results in an APB→SISF transformation.The study also discovered that Pt3 Hf exhibits normal yield behavior,although the cross-slip of a a/2<110> dislocation is not forbidden,and the anomalous yield criterion is satisfied.Moreover,it is observed that the energy barrier and critical stress for APB formation increases with increasing pressure and decreases as the temperature is elevated.When the temperature rises above 1400 K,the a/2<110> dislocation slipping may change from the {111} planes to the {100} planes.