Numerical Investigation into the Effect of Splats and Pores on the Thermal Fracture of Air Plasma-Sprayed Thermal Barrier Coatings

The effect of splat interfaces on the fracture behavior of air plasma-sprayed thermal barrier coatings (APS-TBC) is analyzed using finite element modeling involving cohesive elements. A multiscale approach is adopted in which the explicitly resolved top coat microstructural features are embedded in a larger domain. Within the computational cell, splat interfaces are modeled as being located on a sinusoidal interface in combination with a random distribution of pores. Parametric studies are conducted for different splat interface waviness, spacing, pore volume fraction and fracture properties of the splat interface. The results are quantified in terms of crack nucleation temperature and total microcrack length. It is found that the amount of cracking in TBCs actually decreases with increased porosity up to a critical volume fraction. In contrast, the presence of splats is always detrimental to the TBC performance. This detrimental effect is reduced for the splat interfaces with high waviness and spacing compared to those with low waviness and spacing. The crack initiation temperature was found to be linearly dependent on the normal fracture properties of the splat interface. Insights derived from the numerical results aid in engineering the microstructure of practical TBC systems for improved resistance against thermal fracture

Crystal structure of catena-poly[[cadmium(II)-di-μ2-bromido-μ2-l-proline-κ2O:O′] monohydrate]

In the title coordination polymer, {[CdBr2(C5H9NO2)]·H2O}n, the CdII ion is coordinated by four bromido ligands and two carboxylate oxygen atoms of two symmetry-related proline ligands, which exist in a zwitterionic form, in a distorted octahedral geometry. There is an intramolecular N—H...O hydrogen bond between the amino group and the carboxylate fragment. Each coordinating ligand bridges two CdII atoms, thus forming polymeric chains running along the c-axis direction. The water molecules of crystallization serve as donors for the weak intermolecular O—H...O and O—H...Br hydrogen bonds that link adjacent polymeric chains, thus forming a three-dimensional structure. N—H...O and N—H...Br hydrogen bonds also occur

Effect of process parameters on tire pyrolysis: a review

309-315This review presents pyrolysis of scrap tires with a focus on effect of process parameters (reactor temperature, gas flow rate and catalyst-tire ratio) on yield. Three commercially important pyrolysis by-products from scrap tires are carbon residue, pyrolitic oil and pyro-gas. Pyrolysis of scrap tire starts at 250°C and gets completed at 550°C. Presence of catalysts produces lighter oil with a drastic increase in the concentration of single ring aromatics

Fabrication and Characterization of CU/B4C Surface Dispersion Strengthened Composite using Friction Stir Processing

Friction stir processing has evolved as a novel method to fabricate surface metal matrix composites. The feasibility to make B4 C particulate reinforced copper surface matrix composite is detailed in this paper. The B4 C powders were compacted into a groove of width 0.5 mm and depth 5 mm on a 9.5 mm thick copper plate. A tool made of high carbon high chromium steel; oil hardened to 63 HRC, having cylindrical profile was used in this study. A single pass friction stir processing was carried out using a tool rotational speed of 1500 rpm, processing speed of 40 mm/min and axial force of 10 kN. A defect free interface between the matrix and the composite layer was achieved. The optical and scanning electron micrographs revealed a homogeneous distribution of B4 C particles which were well bonded with the matrix. The hardness of the friction stir processed zone increased by 26% higher to that of the matrix material.Zgrzewanie tarciowe ewoluowało jako nowa metoda wytwarzania kompozytów powierzchniowych z osnową metaliczną. W pracy szczegółowo opisano możliwość wytworzenia kompozytu na powierzchni miedzi zbrojonego cząstkami B4 C. Proszki B4 C sprasowano w rowku o szerokości 0,5 mm i głębokści 5 mm wykonanym na blasze miedzianej o grubości 9,5 mm. Do wytworzenia kompozytu użyto narzędzia o profilu cylindrycznym, z wysokowęglowej stali o wysokiej zawartości chromu, hartowanego w oleju do 63 HRC. W jednym przebiegu obróbki zgrzewanie przeprowadzono przy prędkości obrotowej narzędzia 1500 obr/min. szybkości przesuwu 40 mm/min i osiowej siły 10 kN. Osiągnięto cel w postaci pozbawionego wad połączenia pomiędzy matrycą i warstwą kompozytu. Mikrofotografie optyczne i ze skaningowej mikroskopii elektronowej wykazały jednorodną dystrybucję cząstek B-C, które były dobrze połączone z matrycą. Twardość strefy zgrzewnej tarciowo wzrosła o 26% w stosunku do materiału matrycy