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Papers by Christopher Macey
Applications of Surface Science, 1985
A borosilicate glass (Coming No. 7052) was bonded to an iron, nickel, cobalt alloy (Kovar ASTM F1... more A borosilicate glass (Coming No. 7052) was bonded to an iron, nickel, cobalt alloy (Kovar ASTM F15 alloy) by firing at 900°C in flowing nitrogen, air or oxygen. The shear strength of the resulting seal was determined using a universal testing machine (Instron) and could be correlated with the oxygen partial pressure of the firing atmosphere. The oxygen-fired samples showed the strongest bonding, yielding an average failure stress of 6.3 f 0.4 MPa. The samples fired in air or nitrogen exhibited average failure stresses of 4.5kO.3 MPa and 3.6kO.4 MPa. The fracture surfaces were examined using scanning electron microscopy (SEM) to determine fracture morphology and failure mode. Electron spectroscopy for Chemical Analysis (ESCA) was used to characterize the composition of the fracture surfaces. Surface elemental compositions determined using ESCA were consistent with the failure mechanisms suggested by SEM analysis. Additional Kovar samples were degreased, decarburized, preoxidized and subjected to the same firing schedule and atmospheres as the Kovar-glass seals. ESCA analysis of the fired alloy samples showed the surfaces to be depected in nickel and enriched in cobalt relative to the bulk composition. The extent of cobalt enrichment could be correlated with firing atmosphere.
Microscopy and Microanalysis
In this paper we describe the Shimadzu EPMA-8050G, a novel field-emission EPMA that utilizes a pa... more In this paper we describe the Shimadzu EPMA-8050G, a novel field-emission EPMA that utilizes a patented optics design and x-ray take off angles as high as 52.5 degrees to obtain high spatial resolution at high beam currents. Beam conditions of 20nm@10nA and maximum 3 µA beam current are achievable. This improved design allows EPMA elemental analysis to be utilized in new applications that require both high spatial resolution and high elemental sensitivity. The probe size, which is the main factor of spatial resolution, increases with increasing beam current. At a certain current threshold, Ith, there is an increase in the rate at which the probe size increases with beam current. The factors which influence this threshold were investigated and optimized. A derived formula (1) was used for this research [1] [2].
MRS Proceedings, 1985
ABSTRACTSlagging difficulties encountered in large, pulverized coal-fired utility boilers can be ... more ABSTRACTSlagging difficulties encountered in large, pulverized coal-fired utility boilers can be alleviated by using recently developed chemical conditioners designed to inhibit the agglomeration of molten fly ash particles. Slagging results from the impaction and accretion on the boiler interior surfaces of molten ash particles in the flue gas resulting from the combustion of coal. Electron Spectroscopy for chemical Analysis (ESCA) and ion sputtering depth profiling were utilized to examine the mechanism whereby a fuel conditioner containing copper oxychloride effectively reduced slag deposition rates during a pilot-scale, pulverized coal combustion experiment.
Applications of Surface Science, 1985
A borosilicate glass (Coming No. 7052) was bonded to an iron, nickel, cobalt alloy (Kovar ASTM F1... more A borosilicate glass (Coming No. 7052) was bonded to an iron, nickel, cobalt alloy (Kovar ASTM F15 alloy) by firing at 900°C in flowing nitrogen, air or oxygen. The shear strength of the resulting seal was determined using a universal testing machine (Instron) and could be correlated with the oxygen partial pressure of the firing atmosphere. The oxygen-fired samples showed the strongest bonding, yielding an average failure stress of 6.3 f 0.4 MPa. The samples fired in air or nitrogen exhibited average failure stresses of 4.5kO.3 MPa and 3.6kO.4 MPa. The fracture surfaces were examined using scanning electron microscopy (SEM) to determine fracture morphology and failure mode. Electron spectroscopy for Chemical Analysis (ESCA) was used to characterize the composition of the fracture surfaces. Surface elemental compositions determined using ESCA were consistent with the failure mechanisms suggested by SEM analysis. Additional Kovar samples were degreased, decarburized, preoxidized and subjected to the same firing schedule and atmospheres as the Kovar-glass seals. ESCA analysis of the fired alloy samples showed the surfaces to be depected in nickel and enriched in cobalt relative to the bulk composition. The extent of cobalt enrichment could be correlated with firing atmosphere.
Microscopy and Microanalysis
In this paper we describe the Shimadzu EPMA-8050G, a novel field-emission EPMA that utilizes a pa... more In this paper we describe the Shimadzu EPMA-8050G, a novel field-emission EPMA that utilizes a patented optics design and x-ray take off angles as high as 52.5 degrees to obtain high spatial resolution at high beam currents. Beam conditions of 20nm@10nA and maximum 3 µA beam current are achievable. This improved design allows EPMA elemental analysis to be utilized in new applications that require both high spatial resolution and high elemental sensitivity. The probe size, which is the main factor of spatial resolution, increases with increasing beam current. At a certain current threshold, Ith, there is an increase in the rate at which the probe size increases with beam current. The factors which influence this threshold were investigated and optimized. A derived formula (1) was used for this research [1] [2].
MRS Proceedings, 1985
ABSTRACTSlagging difficulties encountered in large, pulverized coal-fired utility boilers can be ... more ABSTRACTSlagging difficulties encountered in large, pulverized coal-fired utility boilers can be alleviated by using recently developed chemical conditioners designed to inhibit the agglomeration of molten fly ash particles. Slagging results from the impaction and accretion on the boiler interior surfaces of molten ash particles in the flue gas resulting from the combustion of coal. Electron Spectroscopy for chemical Analysis (ESCA) and ion sputtering depth profiling were utilized to examine the mechanism whereby a fuel conditioner containing copper oxychloride effectively reduced slag deposition rates during a pilot-scale, pulverized coal combustion experiment.