Preparation of yttrium oxide coating with enhanced thermal shock resistance on refractories used for titanium alloy melting and casting

In order to enhance the service life of refractories for melting and casting of titanium alloy,preparation of yttrium oxide coatings on the refractories surface is an effective solution.The improvement of thermal shock stability of the coating is beneficial to its spalling resistance during the high-temperature service,and the available slurry with good performance is the prerequisite.The effects of the varieties and contents of dispersant(sodium tripolyphosphate,sodium hexametaphosphate,sodium pyrophosphate,citric acid and polycarboxylate ammonium salt)and binder(aluminum dihydrogen phosphate,zirconium acetate and yttria sol)on the stability,rheological and thixotropic properties of yttrium oxide waterbased slurry were investigated,and the effects of slurry composition design on the thermal shock resistance of the coating were focused.The results showed that the introduction of polycarboxylate ammonium salt as dispersant significantly improved the stability of the slurry,and the varieties of the binders had significant effects on the dispersibility of the slurry.When aluminum dihydrogen phosphate and polycarboxylate ammonium salt were used as binder and dispersant,respectively,the slurry had better stability,suitable rheological and thixotropic properties.By using aluminum dihydrogen phosphate as binder,the coating had good thermal shock resistance and no obvious cracks were observed for the coating after thermal shock,which was attributed to the yttrium aluminate binding phase generated in the coating.An effective method was provided for preparing yttrium oxide coatings with enhanced thermal shock resistance applied in the process of titanium alloy melting and casting.

Chemical constituents from the stem of Embelia laeta

In the present study,we aimed to investigate the chemical constituents from Embelia laeta.The constituents were separated by various column chromatography,including silica gel,ODS gel,MCI gel,Sephadex LH-20,and semipreparative HPLC.Their structures were elucidated by spectroscopic means.A total of 13 compounds were isolated from E.laeta and identified as(6R,9R)-1-Oxo-α-ionol-9-O-β-D-goucopyranoside(1),(+)-Pinoresinol(2),Leptolepisol D(3),Kaempferol(4),Kaempferol-3-α-L-Ramnopyranoside(5),Kaempferol-3-β-D-(6-O-trans-p-coumaroyl) glucopyranoside(6),Bis(2-ethylhexyl) phthalate(7),2-Benzenedicarboxylic diisobutyl ester(8),Caffeic acid methyl ester(9),Paldehyde(10),Coniferaldehyde(11),Caffeic acid(12)and 5-Hydroxymethyl furfural(13),respectively.All the compounds were isolated from E.laeta for the first time.