Microweighing in Vacuum and Controlled Environments

Microweighing in Vacuum and Controlled Environments

1st Edition - January 1, 1980

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  • Editors: A.W. Czanderna, S.P. Wolsky
  • eBook ISBN: 9780444596468

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Methods and Phenomena, 4: Their Applications in Science and Technology: Microweighing in Vacuum and Controlled Environments focuses on the principles, methodologies, and approaches involved in micro mass measurements. The selection first elaborates on introduction and microbalance review, beam microbalance design, construction and operation, and sources of error in microweighing in controlled environments. Discussions focus on Brownian motion, Knudsen forces, gravitational forces, microbalance construction and operation, auxiliary equipment for operation of a vacuum microbalance, undesirable disturbances or forces, calibration techniques, and classification of various types of microbalances. The text then takes a look at physical adsorption studies and chemisorption studies with the vacuum microbalance, simultaneous microgravimetric and residual gas analyzer measurements, and simultaneous measurement of mass change and infrared spectra. Topics include chemisorption results obtained on other solids and silver powders, probing the surface phase, quantitative information from adsorption and desorption, measuring techniques, and examples of physisorption measurements and their evaluation. The manuscript examines unusual applications of the vacuum microbalance and high temperature reaction studies, as well as empirical and theoretical rate laws, permeation of water vapor through plastic membranes, and measurement of permittivity and dielectric loss factor. The selection is a valuable source of data for researchers wanting to explore microweighing in vacuum and controlled environments.

Table of Contents

  • Preface

    Chapter 1. Introduction and Microbalance Review

    I. Introduction

    II. History

    III. Definitions

    IV. Classifications of Various Types of Microbalance

    A. Introduction: The Ideal Microbalance

    B. Types of Instruments

    C. Methods of Monitoring Mass Changes

    D. Methods for Automatic Sensing of Movement from the Null Point

    E. Materials for Microbalance Fabrication

    F. Conclusion: The Ultimate Microbalance

    V. Calibration Techniques

    VI. Auxiliary Equipment for Operation of a Vacuum Microbalance

    A. Introduction

    B. Vacuum Operation

    C. Vibrational Mounts

    D. Thermostatic Operation

    E. Automatic Operation

    F. Manual Operation

    G. High Temperature Operation

    H. Low Temperature Operation

    VII. Undesirable Disturbances or Forces

    A. Adsorption and Desorption Effects

    B. Temperature Fluctuations

    C. Static Charge Forces

    D. Convection Currents

    E. Buoyancy Forces

    F. Radiometric Forces that Result from the Thermomolecular Flow of Gases

    G. Water Vapor Effects

    VIII. Applications

    A. Classic Operation

    B. Simultaneous Measurement of Mass and Other Physical Parameters

    C. Future

    D. Thermogravimetry



    Chapter 2. Beam Microbalance Design, Construction and Operation

    I. Introduction

    II. Some General Theoretical Considerations in Beam Microbalance Design

    III. Microbalance Selection Considerations

    A. Environmental and Experimental Considerations

    B. Advantages and Disadvantages of Various Beam Microbalances

    IV. Microbalance Construction

    A. Materials Considerations

    B. Beam and Suspension Construction

    V. Microbalance Operation

    A. Deflection Detectors

    B. Compensation and Null Techniques

    C. Automatic Damping and Nulling Systems

    D. System Sensibility or Resolution

    E. Microbalance Calibration

    VI. Summary


    Chapter 3. Sources of Error in Micro Weighing in Controlled Environments

    I. Introduction

    II. Brownian Motion

    A. The Undamped Balance Without Feedback

    B. The Critically Damped Balance without Feedback

    C. The Automated Balance

    III. Knudsen Forces

    IV. Cavity Forces

    V. Armlength Effect

    VI. Radiation Pressure

    VII. Gravitational Forces

    VIII. Electrostatic Forces

    IX. Magnetostatic Forces

    X. Building Vibrations


    Chapter 4. Physical Adsorption Studies with the Vacuum Microbalance

    I. Introduction

    II. Instrumentation

    A. Sorption Balances

    B. Instruments for Pressure Measurement and Control

    C. Instruments for Temperature Measurement and Control

    D. Determination of the Saturation Vapor Pressure

    E. Gravimetric Sorption Measuring Instruments

    III. Measuring Techniques

    A. Measuring Procedure

    B. Pretreatment of the Materials

    C. Pretreatment of the Instrument

    D. Special Recommendations for the Measurements

    E. Reducing the Measuring Time

    IV. Examples of Physisorption Measurements and their Evaluation

    A. Evaluation of Adsorption Isotherms

    B. Determination of Specific Surface Area, Particle Size and Roughness

    C. Isotherms of Porous Materials

    D. Mesopore Analysis

    E. Micropore Analysis

    F. Determination of the Isosteric Heat


    Chapter 5. Chemisorption Studies with the Vacuum Microbalance

    I. Introduction

    II. Probing the Surface Phase

    III. Quantitative Information from Adsorption and Desorption

    A. Adsorption Parameters

    B. Isosteric Heat of Adsorption

    C. Activation Energy of Adsorption

    D. Desorption Kinetics

    IV. Experimental

    A. Overview

    B. Apparatus

    C. Technique

    V. Chemisorption Results Obtained on Silver Powders

    A. The Effectiveness of Outgassing, Oxygen Adsorption, and Chemical Reduction for Cleaning the Surface and Producing Reproducible Chemisorptive Behavior

    B. Adsorption and Desorption of Oxygen on Silver

    C. Adsorption of Carbon Dioxide on Oxygen Covered Silver

    VI. Chemisorption Results Obtained on Other Solids

    VII. Concluding Remarks



    Chapter 6. Simultaneous Microgravimetric and Residual Gas Analyzer Measurements

    I. Introduction

    II. Instrumentation

    A. Mass Spectrometers

    III. Experimental

    A. System Design

    B. Methods

    IV. Applications

    A. Review

    B. Future Applications



    Chapter 7. The Simultaneous Measurement of Mass Change and Infrared Spectra

    I. Introduction

    II. Experimental

    III. Results

    IV. Conclusion


    Chapter 8. Microgravimetric Studies of Catalysts and Catalytic Processes

    I. Introduction

    II. Vacuum Microbalances

    A. Equipment and Apparatus

    B. Assembly and Operation

    III. Selected Examples

    A. Surface Area Determination: Variation with Pretreatment

    B. Surface Area Determination: Mixed Physical and Chemical Adsorption

    C. Chemisorption: Rehydration

    D. Support Information: Heat of Adsorption from Heat of Wetting

    E. Sorption Energetics and Mechanism: Lunar Soils

    IV. Areas of Additional Research

    V. Conclusions



    Chapter 9. High Temperature Reaction Studies

    I. Introduction

    A. Types of Chemical Reactions

    B. Purpose of Chapter

    C. Preliminary Thermochemical Analyses

    D. Extent of Reaction

    E. Units

    II. Empirical and Theoretical Rate Laws

    A. General

    III. Apparatus and Methods

    A. Static Reaction Systems

    B. Flow Reaction Systems

    C. Special Problems

    IV. Applications

    A. Vapor Pressure of Silicon

    B. Oxidation of Graphite Using the Static Reaction System

    C. Oxidation of Graphite Using the Flow Reaction System

    D. Oxidation of Molybdenum-Static Reaction System

    E. Oxidation of Tungsten

    V. General Comments

    VI. Appendix 1: Theory of Surface Interface Reactions with no Oxides Present

    A. Processes

    B. Kinetic Theory

    C. Absolute Reaction Rate Theory

    VII. Appendix 2: Furnaces for Temperatures Up to 1650°C

    A. Mechanical and Physical Properties of Molybdenum Disilicide Elements

    B. Electrical Supply Equipment

    C. Useful Life

    D. Atmospheric Effects

    E. Furnace Design: Refractories

    VIII. Appendix 3: Furnace Tubes and Reaction Systems

    A. Criteria of Furnace Tube Performance

    B. Types of Furnace Tubes

    C. Specimen Supporting Wires


    Chapter 10. Unusual Applications of the Vacuum Microbalance

    I. Introduction

    II. Permeation of Water Vapor through Plastic Membranes

    A. Theory of Permeation

    B. Measurement of Permeation

    III. Measurement of Dust Concentration

    A. The Basic Concept of the Dust Balance

    B. Combination of Electrostatic Precipitation and Electromagnetic Weighing

    C. Mass Determination by Vibrations of a Very Thin Band

    IV. Determination of Grain Size Distributions by Weighing

    A. Theory of Sedimentation Analysis

    B. Grain Size Distribution by Sedimentation in Liquids

    C. Grain Size Distribution by Sedimentation in Air

    D. Grain Size Distribution by Sedimentation in Partial Vacuum

    E. General Considerations

    V. Measurement of Surface Tension

    A. Basic Facts

    B. Measurement of Surface Tension with the Aid of Wire Loops and Rings

    C. Measurement of Surface Tension with the Aid of an Immersed Solid Plate

    D. Measurement of Surface Tension with the Aid of a Cylinder or of a Solid Plate Touching the Surface

    E. Adaptation of the Vacuum Microbalance to Measurement of Surface Tension

    VI. Measurement of Permittivity and Dielectric Loss Factor

    A. Theory of Electrostatic Forces on Dielectric Bodies

    B. Measurement of Dielectric Permittivity

    C. Measurement of the Dielectric Loss Factor

    VII. Precision Measurement of Pressure Using the Principle of Automatic Compensation

    A. Objective of the Development

    B. A Self Compensating Bodenstein Manometer

    VIII. Simultaneous Measurement of Components of Force and Combinations of Force and Torque

    A. Measurement of Lift and Drag in a Gas Stream by a Two Component Microbalance

    B. Simultaneous Determination of Mass Flow and Reaction Force of a Vapor Stream from a Heated Sample

    C. Simultaneous Measurement of Weight and Torque by Magnetic Suspension

    IX. Conclusion



Product details

  • Language: English
  • Copyright: © North Holland 1980
  • Published: January 1, 1980
  • Imprint: North Holland
  • eBook ISBN: 9780444596468

About the Editors

A.W. Czanderna

S.P. Wolsky

Affiliations and Expertise

1900 Cocoanut Road, Boca Raton, Florida, FL 33432, USA

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