摘要:

The characteristic surface segregation of both impurities as well as major alloy constituents in 21Cr–6Ni–9Mn (21–6–9), a nitrogen strengthened austenitic stainless steel, has been studied using scanning Auger microscopy (SAM), x‐ray photoelectron spectroscopy (XPS), and sputter Auger techniques. Segregation effects were examined for polycrystalline material heated to temperatures ranging up to 800° C. The SAM results show both a nonuniform spatial distribution of the various segregating species, as well as a strong cosegregation of boron with nitrogen at temperatures above approximately 700° C. Based on a bulk concentration of less than 10 ppm, the resulting surface‐to‐bulk concentration ratio for boron is greater than approximately 5×104. Both the boron and nitrogen Auger and XPS spectra associated with commercially available boron nitride material are identical to those obtained from the segregated layer on 21–6–9 and indicate that the boron and nitrogen cosegregate to form a boron nitride surface layer. This segregated BN layer, which initially is formed at high temperatures and uniformly covers the surface after one hour of heating, is found to be stable down to room temperature. The observed Auger peak positions are compared with semiempirically calculated values based on the XPS results.

ISSN:0022-5355    

DOI:10.1116/1.570117

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

A satellite in orbit is moving at a much higher velocity than most of the ambient molecules, so that it leaves a wake swept nearly free of gas. A concave shield with a large opening into this wake can thus contain a region of low pressure for experiments and provide a high speed pump for experiment outgassing. Potential experiments in this environment include the production of ultrapure materials and deposition of thin films. It is possible to set bounds on the flux density within a wake shield relative to the externally incident flux density on the shield opening. The upper bound of this ratio, for an aft‐facing shield, is simply 1.0, corresponding to a Maxwellian incident flux. The lower bound for a hemispherical shield is 0.5, when the incident flux is all concentrated on the edge around the opening. The lower bound for cylinders of various L/R ratios with the same edge concentration is also very near 0.5. The total flux on a hemisphere from an internal isotropic point source is 1.0 to 1.5 times the flux leaving the point, depending on its location.

ISSN:0022-5355    

DOI:10.1116/1.570118

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

The thermal outgassing and helium permeation characteristics of Code 9658 machinable glass–ceramic are discussed. Up to 600° C, it is shown that this material can be treated like glass vacuum system components. The quantities of outgassing constituents under vacuum conditions are given and the need for vacuum baking freshly machined material is demonstrated. Although the material can be used up to 1000° C, between 600° and 1000° C some fluorine evolution from the material takes place and could present a corrosion problem to some systems. Helium permeability of this material is an order of magnitude lower than for Code 7740 glass.

ISSN:0022-5355    

DOI:10.1116/1.570119

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

A system for measurements of gas pressure in the range 0.5–10−2Pa is described. A known pressure is produced by static gas expansion and compared with the pressure in a scattering cell using a capacitance manometer as the null detector. The pressure in the scattering cell is controlled by a separate dynamic expansion system. Sources of error are discussed and the absolute error is estimated to be 0.4% at 0.5 Pa, 0.5% at 0.1 Pa, and 2.3% at 10−2Pa.

ISSN:0022-5355    

DOI:10.1116/1.570120

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

Platinum sputtering in argon–oxygen mixtures is studied utilizing the technique of glow discharge mass spectrometry which involves penning ionization in the plasma and analysis in a quadrupole filter. (AIP)

ISSN:0022-5355    

DOI:10.1116/1.570121

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

An experimental study of titanium deuteride decomposition utilizing Auger electron spectroscopy is described. (AIP)

ISSN:0022-5355    

DOI:10.1116/1.570122

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

A method is described for the rapid and accurate measurement of the pressure and volume of gas containing devices and the internal volume of vacuum systems; a ratio of pressure measurements and a reference volume are the only requirements. (AIP)

ISSN:0022-5355    

DOI:10.1116/1.570123

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

Comparison of pressure readings in the ’’rough vacuum’’ region of he Granville–Phillips vacuum gauge with two other gauges reveals large discrepancies for helium, methane, argon, and krypton measurements. (AIP)

ISSN:0022-5355    

DOI:10.1116/1.570124

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

The ion pumping characteristics of high voltage 60 Hz ac and dc crossed field discharges, using permanent magnets, are compared. Vacuum insulation, it is suggested, becomes a low cost alternative to permanently sealed equipment.(AIP)

ISSN:0022-5355    

DOI:10.1116/1.570125

出版商:American Vacuum Society    

年代:1979

数据来源: AIP

摘要:

This communication adds further data to the discussion of implantation temperatures for III–V compounds recently published by Gamoetal. Amorphization of InP by ion implantation can be avoided by heating the target to 150° C. Postimplantation annealing of amorphous layers can be done within 30 min at 500° C under phosphorus pressure but noticeable residual damage is left.

ISSN:0022-5355    

DOI:10.1116/1.570126

出版商:American Vacuum Society    

年代:1979

数据来源: AIP