Elimination of cracks in stainless steel casings via 3D printed sand molds with an internal topology structure

The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects are prone to occur.This leads to an increase in the scrap rate of casings,causing significant resource wastage.Additionally,the presence of cracks poses a significant safety hazard after the casings are put into service.The generation of different types of crack defects in stainless steel casings is closely related to casting stress and the high-temperature concession of the sand mold.Therefore,the types and causes of cracks in stainless steel casing products,based on their structural characteristics,were systematically analyzed.Various sand molds with different internal topology designs were printed using the 3DP technology to investigate the impact of sand mold structures on high-temperature concession.The optimal sand mold structure was used to cast casings,and the crack suppression effect was verified by analyzing its eddy current testing results.The experimental results indicate that the skeleton structure has an excellent effect on suppressing cracks in the casing.This research holds important theoretical and engineering significance in improving the quality of casing castings and reducing production costs.

A thermochemical model description of CaO_(2)-SiO2-Al_(2)O_(3) silicate system

A thermochemical model based on the ion and molecule coexistence theory(IMCT)was developed to calculate thermodynamic data in the CaO-SiO_(2)-Al_(2)O_(3) slag system,considering the influential role of oxide activities on the thermodynamic properties of slags.Using this model,iso-activity contours were obtained for oxide components CaO,SiO_(2) and Al2O3 in this system at temperatures of 1,873 K and 1,773 K.When compared with the IMCT model,it is found that the predicted activities of oxide components in the CaO-SiO_(2)-Al_(2)O_(3) system using the model developed in this study better matches experimental data from literature in terms of both trend and numerical value.Therefore,the model developed in this study can serve as a robust modeling tool for metallurgical processes,and the thermodynamic data predicted by this new model can be used to improve the metallurgical technology.

Selective Aggregation of Silver Nanoprisms Induced by Monohydrogen Phosphate and its Application for Colorimetric Detection of Chromium(Ⅲ) Ions

In this study,we established a simple colorimetric method for visual detection of chromium(Ⅲ)ions using aggregated silver nanoprisms induced by monohydrogen phosphate.The detection strategy had two steps,selective aggregation of silver nanoprisms with monohydrogen phosphate at high temperature,and anti aggregation of silver nanoprisms in the presence of chromium(Ⅲ)ions.In this strategy,significant spectral shift of the localized surface plasmon resonance(LSPR)absorption peak of silver nanoprisms could be visualized with the color changed from yellow to blue.The spectral peak shift of silver nanoprisms in the anti-aggregation process was linear with the concentrations of the added chromium(Ⅲ)ions in the range of 20.0-800.0 nM.Thus,a colorimetric method for chromium(Ⅲ)ions detection was established with the detection limit of 3.6 nM.The experimental results of real water samples indicated that the colorimetric sensor was potential in environmental monitoring.