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in creator/contributor: "Hou, P."

open access

Distribution of Ion-Implanted Yttrium in Cr2O3 Scale and in the Underlying Ni-25wt%Cr Alloy

Implantation of yttrium and other reactive metals has been known to show significant effects on the oxidation behavior of Cr{sub 2}O{sub 3}-forming alloys. The oxide growth rate decreases by nearly a factor of ten, and the adhesion of oxide scales to alloys is greatly improved. To better understand the mechanisms by which these elements affect oxidation, it is important to know whether or not they are present in the metal ahead of the oxide layer. In this study, the diffusivity of implanted ytt… more

Date: July 1, 1991

Creator: Hou, P. Y.; Brown, I. & Chia, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Promises and problems with metallic interconnects for reduced temperature solid oxide fuel cells

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Date: May 1, 1999

Creator: Hou, P.Y.; Huang, K. & Bakker, W.T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Study of the Effect of Reactive Element Addition by Implanting Metal Ions in a Pre-Formed Oxide Layer

The influence of ion-implanted Y, Hf, Zr and Cr on the oxidation behavior of a Ni-25 wt % CR alloy at 1000{degrees}C has been investigated. The implantation dosage was 5 {times} 10{sup 16} ions/cm{sup 2}. Two methods of implantation have been used. One was to implant ions directly into a clean alloy surface; the other was to implant into an approximately 0.6 {mu}m thick Cr{sub 2}O{sub 3} layer formed at 1000{degrees}C on the alloy. In neither case did the Cr implantation show any beneficial eff… more

Date: September 1, 1990

Creator: Hou, P. Y.; Brown, I. G. & Stringer, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Methods of measuring adhesion for thermally grown oxide scales

High temperature alloys and coatings rely on the formation of adherent scales to protect against further oxidation, but scale spallation is often problematic. Despite the technical importance of the problem, ``practical adhesion``, which refers to the separation of the oxide from the metal, has mainly been treated qualitatively in the past. Various techniques now exist such that the subject can be assessed in quantitative or semi-quantitative terms. Some of the techniques are described in this … more

Date: June 1, 1994

Creator: Hou, P. Y. & Atkinson, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The oxidation behavior of Co-15 wt % Cr alloy containing dispersed oxides formed by internal oxidation

Internal oxidation pretreatments of Co-15wt%Cr and Co-15wt%Cr-1wt%Ti were carried out using a Rhines pack in quartz, in mullite and in alumina. A dispersion of titanium oxide particles formed in the Ti-containing alloy as a result of the internal oxidation. However, silicon also diffused into all treated specimens when the pretreatments were carried out in quartz or in mullite. The effect of various pretreatments on the subsequent oxidation of these alloys was studied at 1000{degree}C, and comp… more

Date: December 1, 1991

Creator: Hou, P.Y.; Shui, Z. R. & Stringer, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The oxidation behavior of Co-15 wt % Cr alloy containing dispersed oxides formed by internal oxidation

Date: December 1, 1991

Creator: Hou, P. Y.; Shui, Z. R. & Stringer, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Growth strains and stress relaxation in alumina scales during high temperature oxidation

A novel X-ray technique was used, exploiting synchrotron radiation at the Advanced Photon Source at Argonne National Laboratory, to investigate the growth stresses in {alpha}-Al{sub 2}O{sub 3}. In-situ measurements of Debye-Scherrer diffraction patterns from the scale were recorded during oxidation and cooling, and the elliptical distortion of the diffraction rings was analyzed to yield the in-plane strain. Fe-28Al, Fe-40Al, Fe-40Al-0.2Hf, Fe-20Cr-10Al and Ni-50Al (at. %) were studied. Data wer… more

Date: March 23, 2004

Creator: Hou, P.Y.; Paulikas, A.P. & Veal, B.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Development of Chemically Vapor Deposited Mullite Coatings for the Corrosion Protection of SiC

Crystalline mullite coatings have been chemically vapor deposited onto SiC substrates to enhance the corrosion and oxidation resistance of the substrate. Current research has been divided into three distinct areas: (1) Development of the deposition processing conditions for increased control over coating`s growth rate, microstructure, and morphology; (2) Analysis of the coating`s crystal structure and stability; (3) The corrosion resistance of the CVD mullite coating on SiC.

Date: May 1, 1998

Creator: Auger, M.; Hou, P.; Sengupta, A.; Basu, S. & Sarin, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Stress Development and Relaxation in Al2O3 during Early StageOxidation of beta-NiAl

Using a glancing synchrotron X-ray beam (Advanced Photon Source, Beamline 12BM, Argonne National Laboratory), Debye-Scherrer diffraction patterns from thermally grown oxides on NiAl samples were recorded during oxidation at 1000 or 1100 C in air. The diffraction patterns were analyzed to determine strain and phase changes in the oxide scale as it developed and evolved. Strain was obtained from measurements of the elliptical distortion of the Debye-Scherrer rings, where data from several rings o… more

Date: April 20, 2005

Creator: Hou, P.Y.; Paulikas, A.P. & Veal, B.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stress determination in thermally grown alumina scales using ruby luminescence

By exploiting the strain dependence of the ruby luminescence line, we have measured the strain in alumina scales thermally grown on Fe-Cr- Al alloys. Results are compared and found to be reasonably consistent with strains determined using x rays. Oxidation studies were carried out on alloys Fe - 5Cr - 28Al and Fe - 18Cr - 10Al (at.%). Significantly different levels of strain buildup were observed in scales on these alloys. Results on similar alloys containing a ``reactive element`` (Zr or Hf) i… more

Date: June 1, 1996

Creator: Renusch, D.; Veal, B. W.; Koshelev, I.; Natesan, K.; Grimsditch & Hou, P. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Strains in Thermally Growing Alumina Films Measured in-situ usingSynchrotron X-rays

Strains in thermally grown oxides have been measured in-situ, as the oxides develop and evolve. Extensive data have been acquired from oxides grown in air at elevated temperatures on different model alloys that form Al{sub 2}O{sub 3}. Using synchrotron x-rays at the Advanced Photon Source (Beamline 12BM, Argonne National Laboratory), Debye-Scherrer diffraction patterns from the oxidizing specimen were recorded every 5 minutes during oxidation and subsequent cooling. The diffraction patterns wer… more

Date: January 2, 2006

Creator: Hou, P.Y.; Paulikas, A.P. & Veal, B.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Sulfur segregation to oxide/metal interfaces: a comparison of thermally grown and plasma deposited Al{sub 2}O{sub 3}

Segregation of S to oxide/metal interfaces was studied using scanning Auger microscopy after removing the oxide film in ultrahigh vacuum. Two types of alumina films were investigated: one formed from oxidation at 1000 C on Fe-28at.%Al-5at.%Cr; the other was deposited on the same alloy via plasma synthesis, where Al was codeposited with O to form an amorphous Al2O3 film, 0.2 or 0.8 {mu}m thick. Subsequent heat treatment of the deposited film at 1000 C caused it to slowly transform to {alpha}-Al2… more

Date: September 1, 1996

Creator: Hou, P. Y.; Wang, Z.; Pruessner, K.; Alexander, K. B. & Brown, I. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Strain measurements in thermally grown alumina scales using ruby fluorescence

We have measured strains in alumina scales thermally grown on Fe-Cr- Al alloys by exploiting the strain dependence of the ruby luminescence line. Measurements were done on Fe-5Cr-28Al and Fe-18Cr-10Al (at.%, bal. Fe) oxidized between 300-1300 C with periodic cycling to room temperature. Significantly different levels of strain buildup were observed in scales on these alloys. Results on similar alloys containing a dilute reactive element (Zr or Hf) are also presented. We observe that scales on a… more

Date: December 31, 1996

Creator: Veal, B. W.; Natesan, K.; Koshelev, I.; Grimsditch, M.; Renusch, D. & Hou, P. Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Finite element modeling of the effect of interface anomalies on thermal stresses in alumina scales

The scales that grow from oxidation often develop a convoluted morphology or interface pores. High thermal stresses can develop locally and are potentially detrimental to the scale or interface integrity. Finite element simulations are used to examine residual thermal stresses and strains that result when these deviations from a flat interface have formed, and the resulting geometry is subsequently cooled to room temperature. A variety of geometries will be considered for alumina scales on a Fe… more

Date: July 1, 1998

Creator: Wright, J. K.; Williamson, R. L.; Hou, P. Y.; Cannon, R. M.; Renusch, D.; Veal, B. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department