Quantification of uf and pf Resins in MDF Fiber with an X-Ray Fluorescence Spectrometer

This article describes methods to quantify urea-formaldehyde (UF) resin and phenol-formaldehyde (PF) resin contents in medium density fiberboard (MDF) using a wavelength dispersive X-ray fluorescence spectrometer (WDXRF). The methods are based on the principle that a specific metallic element shows its characteristic X-ray fluorescence spectrum, the intensity of which is correlated quantitatively to its concentration. In the case of UF-blended MDF fiber, 2.4% copper sulfate pentahydrate CuSO4.5H2O (based on resin solids) was premixed with the resin as a labeling agent. Quantification of copper ion was performed using XRF. Based on calibrations with laboratory-prepared standard fiber samples of known UF resin and copper quantities, the results of XRF measurements were converted to resin loading rates. In the case of PF-blended fiber, the PF resin contents in the MDF fiber samples were successfully quantified by measuring the existing sodium ion Na+ in the resol resin with XRF. Linear calibration curves between fluorescence intensity of copper or sodium and resin content were established respectively for UF and PF resins. Test results show that the methods were precise and reliable

The 1040th Anniversary Celebrations of Yuelu Academy

Introduction of Major Institution

A non-oscillatory multi-moment finite volume scheme with boundary gradient switching

In this work we propose a new formulation for high-order multi-moment constrained finite volume (MCV) method. In the one-dimensional building-block scheme, three local degrees of freedom (DOFs) are equidistantly defined within a grid cell. Two candidate polynomials for spatial reconstruction of third-order are built by adopting one additional constraint condition from the adjacent cells, i.e. the DOF at middle point of left or right neighbour. A boundary gradient switching (BGS) algorithm based on the variation-minimization principle is devised to determine the spatial reconstruction from the two candidates, so as to remove the spurious oscillations around the discontinuities. The resulted non-oscillatory MCV3-BGS scheme is of fourth-order accuracy and completely free of case-dependent ad hoc parameters. The widely used benchmark tests of one- and two-dimensional scalar and Euler hyperbolic conservation laws are solved to verify the performance of the proposed scheme in this paper. The MCV3-BGS scheme is very promising for the practical applications due to its accuracy, non-oscillatory feature and algorithmic simplicity

Investigation of ultra-thin Al₂O₃ film as Cu diffusion barrier on low-k (k=2.5) dielectrics

Ultrathin Al(2)O(3) films were deposited by PEALD as Cu diffusion barrier on low-k (k=2.5) material. The thermal stability and electrical properties of the Cu/low k system with Al(2)O(3) layers with different thickness were studied after annealing. The AES, TEM and EDX results revealed that the ultrathin Al(2)O(3) films are thermally stable and have excellent Cu diffusion barrier performance. The electrical measurements of dielectric breakdown and TDDB tests further confirmed that the ultrathin Al(2)O(3) film is a potential Cu diffusion barrier in the Cu/low-k interconnects system