The Decomposition of Perchloric Acid on Metal Oxide Catalysts

Gilbert, Richard E.; Jacobs, P. W. M.

doi:10.1139/v71-471

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…Further, when an identical mixture was kept at 260 ~ for 10 minutes, extracted with water and filtered, the filtrate gave a positive test for aluminium with alizarin S, suggesting the intermediate formation of aluminium perchlorate. A similar effect has also been observed in the decomposition of perchloric acid in the presence of alumina [14]. …”

Section: Resultssupporting

confidence: 73%

Explosive sensitivity of methylammonium perchlorates

Nambiar

Verneker

Jain

1975

Journal of Thermal Analysis

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The explosive sensitivity of methylammonium perchlorates has been investigated by differential thermal analysis, thermogravimetric analysis, mass spectrometry and explosion delay experiments. The decomposition temperature of these compounds increases in the order CH3NH3C10 ~ > (CH3)zNH2C104 > (CH.~)3NHC104. The activation energy shows the reverse order, indicating thereby that the stability increases with increasing substitution. Mass spectrometric investigation, however, suggests an increasing reactivity with increasing substitution. A possible explanation for such behaviour is proposed. It appears that explosion delay is correlated with thermal decomposition and impact sensitivity.During the past few years there has been increasing interest in the thermal studies of methyl-substituted ammonium perchlorates [1][2][3][4][5]. It is amazing to note that ammonium perchlorate, a comparatively stable compound, becomes almost an explosive on substitution of one or more of its protons by a methyl group [1 ]. The explosion temperature of monomethylammonium perchlorate has been reported to be 338 ~ [6]. The relative thermal stability of the methyl-substituted ammonium perchlorates, however, seems to be dependent upon the technique employed for investigation. For example, from a thermal decomposition study using a mass spectrometer, Guillory and King [3] have concluded that the substitution of methyl groups into the ammonium cation stabilizes these perchlorates. This is based upon their observation that the dissociation temperatures increase with increasing methyl substitution into the cation, i.e. in the order NH4C10~ < < CH3NHzC104 < (CH3)2NH2CIO4 < (CH3)3NHC104. Further, the impact sensitivity results obtained by Stammler et al. [1 ] indicate monomethylammonium perchlorate to be most sensitive, whereas the decomposition temperatures of these compounds as revealed by differential thermal analysis seem to decrease as the methyl substitution increases, showing thereby that their stabilities probably decrease with increasing substitution.Though speculations about the similarity or dissimilarity of the mechanisms of explosion by impact and by heat could be misleading [7], recent work by Pai Verneker and Avrami [8] suggests a definite correlation between the explosive sensitivities of barium azide to heat, impact or friction. The present investigation

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Section: Resultssupporting

confidence: 73%

Explosive sensitivity of methylammonium perchlorates

Nambiar

Verneker

Jain

1975

Journal of Thermal Analysis

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“…[15,16] On a nanoscale, asperities sliding 100 μm or less (i.e., fretting) within the crevices of femoral components can initiate mechanically assisted crevice corrosion (MACC), an autocatalytic mechanism that promotes destructive conditions within the confines of modular taper junctions. [5,14,[17][18][19][20] Potential decreases during MACC cathodically activate the surface and may generate reactive oxygen species (ROS). Previous studies document potentials as negative as -1 V during fretting corrosion of Ti-6Al-4V surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…[ 15,16 ] On a nanoscale, asperities sliding 100 µm or less (i.e., fretting) within the crevices of femoral components can initiate mechanically assisted crevice corrosion (MACC), an autocatalytic mechanism that promotes destructive conditions within the confines of modular taper junctions. [ 5,14,17–20 ]…”

Section: Introductionmentioning

confidence: 99%

Deep Neural Network Predicts Ti‐6Al‐4V Dissolution State Using Near‐Field Impedance Spectra

Kurtz,

Yang,

Liu

et al. 2023

Adv Funct Materials

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Retrieval studies document Ti‐6Al‐4V selective dissolution within crevices of total hip replacement devices. A gap persists in the fundamental understanding of Ti‐6Al‐4V crevice corrosion in vivo and its impact on local impedance. Previous studies use nearfield electrochemical impedance spectroscopy (nEIS) for characterization of retrieved CoCrMo surfaces and phase angle symmetry‐based EIS (sbEIS) for rapid data acquisition. In this study, these methods are combined with a deep neural network to characterize the local impedance changes after selective dissolution. It is hypothesized that structural changes occurring during dissolution will manifest as property changes to the oxide film capacitance. First, after sustained cathodic activation, the Ti‐6Al‐4V β phase selectively dissolves from the surface. Next, nEIS acquires n = 100 control and n = 105 dissolved spectra. Over dissolved regions, oxide capacitance significantly increases (Log10Q = ‐4.17 versus ‐4.78 (Scm−2(s)α), p = 0.000). Using single frequency EIS (5000 Hz), a capacitance‐based scanning impedance microscopy method identifies dissolved regions within seconds. Finally, Bode phase plots of the 205 control and dissolved nEIS spectra are input into a deep neural network. After training with n = 180 spectra, the model predicts the surface state for n = 25 previously unseen nEIS spectra with 96% accuracy.

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