C. L. Putzig

Structures and properties of disordered boron carbide coatings generated by magnetron sputtering

Disordered boron carbide coatings with their high hardness, high lubricity, and low surface friction have become the coatings of choice to enhance the wear performance of many existing products. These coatings have been successfully commercialized using a magnetron sputtering process. In this paper, the effects of one of the critical process parameters, bias voltage, on the chemistry, microstructure, and the properties of the coatings are discussed. In combination with microstructure examination, special emphasis was made on nanoscopic level chemical analyses in order to explain the effects of this process parameter. The substrate bias was found to have strong effects on the hardness and the stress of the coating, but it has little influence on the frictional characteristics of the coating. The results of the examination and the analyses of the coating using FTIR, XPS, TEM, PEELS, and SIMS revealed that the morphology of the coating changed from a columnar structure to a continuous solid structure as the substrate bias voltage increased from 0 to 200 V. Oxide species were found in between the columns, while the columns mainly consisted of boron carbide with a boron to carbon atomic ratio of about 4. The atomic ratio of boron to carbon appeared to be independent of the substrate bias.

Solvent Effect Correlations for Acetone: IR versus NMR Data for the Carbonyl Group:

A linear relationship is found to exist between the carbonyl stretching frequency (vC=O) and the carbon-13 chemical shift data [δ(13C=O)] for the carbonyl group of 0.345 mole % acetone in a mixed solvent solution ranging from 1.5 to 70.8 mole % CHCl3/CCl4. The correlation shows that as vC=O decreases in frequency δ(13C=O) increases in frequency as the concentration of CHCl3 increases in the acetone/CHCl3/CCl4 solutions. However, the relationship between vC=O and the mole % CHCl3/CCl4 and between δ(13C=O) and the mole % CHCl3/CCl4 is not linear over the concentration range studied. Both hydrogen bonding and bulk dielectric effects most likely contribute to the change in both the IR and NMR data with change in the CHCl3/CCl4 ratio.

Solvent and Concentration Effects on Carbonyl Stretching Frequencies: Ketones

Hydrogen bonding, dielectric effects, and steric effects are all factors which determine the carbonyl stretching frequency, vC=O, of ketones in solution. The vC=O frequency for ketones shifts continuously at constant concentration in solutions of CHCl3/CCl4 with change in the mole ratio of the two solvents. The vC=O frequency is also affected by change in concentration in either CCl4 or CHCl3 solution.

Studies of Carbonyl-Containing Compounds in Mixed Solvent Systems by Application of Infrared Spectroscopy

The carbonyl stretching vibrations decrease in frequency in the order of solvent polarity (acetonitrile and nitromethane are exceptions) and in the increasing mole concentration of the more polar solvent of a solvent pair. Intermolecular hydrogen bonding between the chloroform proton and the carbonyl oxygen atom of the solute shifts vC=O to lower frequency. Polar solvents such as dimethyl sulfoxide cause vC=O to shift to lower frequency by interacting with the solute in a manner which induces a canonical form which lengthens and weakens the C=O bond. Steric factors of α-halo or oxy groups of carboxylic acids or ketones prevent close solute/solvent interaction in the gauche rotational isomer compared to the cis rotational isomer; thus, gauche vC=O has a lesser contribution from the induced canonical form due to solute/solvent interaction, and gauche vC=O shifts less to lower frequency than does cis vC=O. The rotational isomer concentration distribution also changes with change in solvent polarity. Thus, physical factors of the solute play a role in solvent-induced chemical shifts of IR group frequencies.

Assignment of the B1 (antisymmetric) ring deformation in ethylene oxide using high-resolution FT-IR

Assignment of the B1 (antisymmetric) ring deformation in ethylene oxide has been the subject of controversy. This B1 vibration should produce a type-A IR band, and Lord and Nolin report a Q-branch peak at 892 cm-1 which they assign as the B1 ring deformation. Thompson and Cave have suggested that the absorption maximum near 840 cm-1 results from this B1 fundamental. Lord and Nolin obtained a vapor-phase IR spectrum of ethylene oxide-d4, and they assigned the 809 cm-1 type-A band to the B1 ring deformation. By application of the product rule for the B1 class in ethylene oxide and ethylene oxide-d4, Lord and Nolin have demonstrated that it is reasonably certain that the B1 antisymmetric ring deformation must occur near 890 cm-1.

Identification of Pentachlorobiphenyl Isomers by Application of Diffuse Reflectance Fourier Transform Infrared Spectroscopy

The IR spectra presented in this paper are useful for scientists engaged in the isolation and identification of polychlorobiphenyl isomers via spectral comparison. IR correlations presented should also be useful in the identification of other polychlorobiphenyl isomers, especially in cases where the mass spectral data for the corresponding fractions are also available.

Vibrational Study of Alkyl Isocyanates in Solution

The vasym. NCO frequencies for alkyl isocyanates occur at higher frequency in CHCl3 solution than in CCl4 solution. With the exception of tert-butyl isocyanate, the vasym. NCO mode increases in frequency as the mole % CHCl3/CCl4 increases. The vasym. NCO mode for tert-butyl analog increases in frequency up to a certain mole % CHCl3/CCl4 and then vasym. NCO decreases in frequency. The vasym. NCO mode for n-butyl isocyanate occurs at an exceptionally high frequency for the alkyl isocyanate studied, and this result is explained in terms of the formation of a pseudo six-membered intermolecular hydrogen-bonded ring. Inductive and steric factors also influence the type and form of solvent/solute complexes formed vs. mole % CHCl3/CCl4 as determined by study of the vasym. NCC frequencies. In general, the vasym. NCO and the vsym. NCO modes for alky isocyanates decrease in frequency as the number of hydrogen atoms on the α-carbon atom of the alkyl group decreases from 3, to 2, to 1, to 0. Some of the alkyl isocyanates exhibit two significant IR bands in the region expected for vasym. NCO, and the methyl analog exhibits three significant bands in this region of the spectrum. These IR bands are the result of vasym. NCO in Fermi resonance with combination tones, and the unperturbed frequencies have been calculated with the use of the recorded data.

Vibrational Assignments of the Epihalohydrins

Liquid-, solution-, solid-, and vapor-phase infrared spectral data have been recorded for the epihalohydrins. The IR data recorded of the various physical phases enables specific band assignment for both rotational isomers. The spatial configuration of the rotational isomer existing in the solid phase is different from the spatial configuration of the rotational isomer existing in the vapor phase, while both spatial configurations exist in the liquid phase or solution phase. Vibrational frequency assignments are aided by comparison with vibrational assignments for the 3-halopropynes and the 3-halopropenes. Raman data are also used in making the vibrational assignments for epichlorohydrin, epibromohydrin, and epiiodohydrin.

Infrared and Raman group frequency correlations: Substituted oxamides

Abstract Infrared and Raman spectra of N,N′-dialkyl oxamides and N,N′-diaryl oxamides or (N,N′-oxanilides) were recorded, and characteristic group frequencies useful in spectra-structure identification are presented. The i.r. and Raman data recorded for N,N′-dialkyl or N,N′-diaryl oxamides in the solid phase can be explained on the basis that they exist in an intermolecularly hydrogen bonded trans configuration where each oxamide group can be viewed as having C2h symmetry. In the vapor phase, N,N′-dimethyloxamide also exists in the trans configuration. Evidence is presented that suggest N,N,N′,N′-tetraethyloxamide exists as rotational isomers in solution, and that these are the trans and gauche structures.

Quantitative Infrared Multicomponent Analysis for Films with Indeterminant Pathlength

Frequently, the need arises for an infrared method of quantitating a number of components in a system that cannot be readily determined by straightforward application of the Beer-Lambert law. Although a number of methods have been proposed, we believe that the following method is much simpler than existing methods for films with indeterminant pathlength.