摘要:

The present article introduces a new technique for window interferometry in the case of combined normal and shear wave motion. The method can, in principle, be used for micromechanical studies of damage and inelasticity in a variety of materials. Preliminary tests conducted on brittle materials indicate the feasibility of the technique and its advantages over other in‐material measurements using embedded manganin gauges or electromagnetic particle velocity gauges. An analysis of the interferometric signals, incorporating variations in the index of refraction of the window material, is used in the interpretation of the velocity histories. The suitability of the technique in the study of dynamic failure and material instabilities is presented. Furthermore, the use of the in‐material measurement technique in the design of pressure‐shear recovery experiments is described. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147294

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A shear light scattering photometer with an optical microscope was constructed for the study of polymer blends in a simple shear field. This instrument utilizes a cone and plate or parallel plate geometry for the generation of shear field. The shear rates are controlled by a microstepping motor. The controllable range of shear rate is between 0.002 and 1000 s−1. The bottom plate of the shear cell has a special design to accommodate the microscope objective and a thin disk‐type heater for temperature control. The accessibleqrange is from 0.7 to 4.6 &mgr;m−1with a 632.8 nm He–Ne laser or from 0.9 to 6.0 &mgr;m−1with a 488 nm Ar ion laser. The temperature can be controlled from ambient temperature to 250 °C with ±0.1 °C accuracy. A phase contrast microscope and a fluorescence microscope are built into this photometer for theinsitumorphological study of materials of interest. The optics for light scattering and microscopy can be switched back and forth by a simple translational movement of a rail‐mounted optical platform, without any realignment, for comparison of data from reciprocal space with that from real space. A bulk polystyrene/polybutadiene blend and a polystyrene/polybutadiene/dioctylphthalate blend were used to demonstrate the performance and versatility of this instrument.

ISSN:0034-6748    

DOI:10.1063/1.1147295

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A bipolar, high‐current (10 000 A) pulse generator, used to magnetically saturate thin films during spin‐polarized electron and dynamic response measurements, is described. Bipolar operation is achieved by discharging a bank of capacitors through selected pairs of high‐power silicon‐controlled rectifiers connected to a coil in an H bridge configuration. The pulse generator can be controlled either manually or by means of a computer. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147296

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A method is proposed for testing the exoemission activity of different metals, used as materials in high sensitivity electrometry (attoammetry). The presented test results allow us to select materials with weaker exoelectron spurious currents. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147297

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A rapid thermal processing system is described incorporating features that enableinsituoptical measurements. In particular, a system incorporating aninsituspectroscopic ellipsometer is described highlighting some of the unusual features necessary for ellipsometry measurements. These features include independent optical, vacuum, and heating modules, optical and heating window design, reflector design, and sample manipulation to enable proper positioning for measurement. Although specifically designed with ellipsometry in mind, many of the same principles used in the design of this system will apply to systems for other optical measurements. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147273

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A reliable high temperature substrate heater for thin film deposition was constructed. The heater has a modular design and is built from parts that are easy to fabricate. The heater consists of a square arrangement of four tungsten filaments in a disk‐shaped molybdenum susceptor. The electrical connections are placed near the edge where they are easily accessed. A finite element analysis shows that this design produces a more uniform temperature distribution than typical radial arrangements of filaments. The excellent performance of the new heater is demonstrated by thickness variations of less than 2% in thin films of lithium tantalate films grown on a 3.75 cm diam substrate by a high vacuum metal‐organic chemical vapor deposition process. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147298

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An instrument is presented which was designed for comprehensivein‐situanalysis of phase formation and transformation during the ion implantation process. An implanter end station with heatable He‐cryostat as a sample holder was built. A temperature range from 4 to 1270 K is covered by the sample holder so that temperature can be varied during implantation or subsequent annealing in high vacuum. Both x‐ray diffraction and four‐point resistivity measurement are installed asin‐situinvestigation techniques. In this way a detailed study of structural changes and defect kinetics during ion bombardment is now possible. The whole instrument has been successfully tested. Examples of carbon ion implantation in titanium and iron are given. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147299

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We describe a time‐domain (pulsed) eddy‐current technique for determining the thickness and conductivity of conductive coatings on metal plates. The pulsed eddy‐current instrument records the transient current induced in an absolute, air‐cored coil placed next to a layered sample and excited with a step‐function change in voltage. Signals are digitized with 16‐bit resolution at a sampling rate of 1 megasamples per second, and the excitation is repeated at a rate of 1 kHz. The instrument displays the difference in the transient current measured on the substrate and on the substrate plus coating. We measured pulsed eddy‐current signals for a series of metal foils of varying thickness placed over 1 cm thick metal plates. Seven combinations of foil and substrate metals were studied including pure aluminum, copper, and titanium foils over substrates of aluminum, titanium alloy, and stainless steel. We report results for three types of samples: aluminum foils on Ti–6Al–4V substrate, titanium foils on 7075 aluminum alloys, and aluminum foils on AISI 304 stainless steel. Foil thickness ranged from 0.04–1.00 mm. We found that three features of the signal—the peak height, the time of occurrence of the first peak, and a characteristic zero‐crossing time—depend sensitively upon the thickness of the layers and the relative electrical conductivity of coating and substrate. Theoretical calculations were compared to the measurements. Absolute agreement between calculated and measured signals was, in most cases, within 3%. No calibration with respect to artifact standards was used. Finally, a feature‐based rapid inversion method was developed and used to infer the thickness and conductivity of the layers. The accuracy of the inversion depends upon the thickness of the layer and the contrast in conductivity between layer and substrate. For the materials studied the thickness could be determined within 13%, while the error in determining conductivity was 20%–30%. The time‐domain method is much simpler and hundreds of times faster than the frequency‐domain method previously reported by Moulderetal. [Rev. Sci. Instrum.63, 3455 (1992)]. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147300

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Rigorous mathematical modeling of the process dynamics associated with the construction and filling of density gradient columns is presented in this article. These models incorporate the hydrostatic driving forces for fluid flow, friction losses associated with this flow, and the unsteady‐state behavior of the liquid levels in the filling vessels and in the column itself. Four different filling arrangements are considered, corresponding to the density order of the two fluids in the filling vessels and two methods for introducing the fluid of varying density into the column. Time requirements for filling of the column and the resulting calibration curve for liquid density versus height in the gradient column are both obtained as a result of this modeling procedure. Further, extremely important operating guidelines for the final achievement of a linear density gradient in the column, which is normally the desired objective in most laboratory applications, are derived and presented. Conversely, the causes leading to nonlinear gradients are elucidated and quantified. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147301

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The thin‐film palladium/hydrogen system was studied using a novel all optical method. Isotherms at room temperature (25 °C) were obtained for palladium films with different thicknesses. The measured isotherms included the &agr;, &agr;‐to‐&bgr;, and &bgr; phase regions. A decrease of the phase transition region was observed as the palladium film thickness was decreased. This optical method has good potential for use in studying the equilibrium and kinetic aspects of any thin‐film/gas system. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147260

出版商:AIP    

年代:1996

数据来源: AIP