can be prepared for use in determining local stressstrain configurations.

Capability: Replica or actual specimen up to 2.5 cm diameter and 1 cm thick. Resolution of 25nm, and maximum magnification of 100,000x. Electron beam of about 10 nm (100Å) diameter is driven across specimen, while secondary electrons, backscattered electrons, and x-rays are each detected and amplified to modify the brightness of a CRT raster. A data acquisition system and data reduction programs are available.

Applications: Behavior of grain boundaries in embrittled copper-palladium welds; checking of resolution using dendrites of aluminum-tungsten; identification of material in micrometeoritic lunar craters; distinguishing chrysotile from termolite; qualitative chemical analysis of microscopic particles; effect of polishing on dental materials; rusting through pinholes in enameled steel; bonding and defects in microcircuitry wafers; hydrogel coating on aortic catheters; wear of currency papers; sharpness of tungsten field-emitter tip.

Availability: To any qualified NBS research worker, after an initial training period. Over 30 NBS scientists have become competent operators. In appropriate instances individual research workers from other Federal organizations can gain access to the facility. Literature: NBS Tech. News Bull., March 1972, Vol. 56, No. 3, pages 60-63.

Contact: Dr. Arthur W. Ruff, Jr., Chief of Microstructures Characterization Section, Materials Building, Room B118, Phone 301-921-2991.

This facilitates specimen preparation, increases foil rigidity, and reduces surface effects.

=

Capability: Accelerating voltages of 50, 100, 150, and 200 kV. Selected area electron diffraction and elecromagnetic beam tilting (±3°) for dark field imaging. Side entry goniometer stage with: double-tilt (X +60°, Y = ±45°), rotation (360°)-tilt (±60), and heating (to 1000° C)-tilt specimen holders for specimens up to 3.05 mm in diameter. Resolution (line) of 0.7 nm (7 Å) and maximum magnification of 150,000x. Data recorded on 34 X 4 inch glass photographic plates. Dispersive x-ray energy analysis. Applications: Examination of the surface regions of various ceramic materials after abrasive, smoothsliding and erosive wear; analysis of deformation and fracture mechanisms in ceramics as a function of temperature; analysis of cracks and crack healing processes in ceramics; microstructure characterization of cemented carbides; determination of stacking fault energy as a function of temperature in Ag-Sn and Au-Sn alloys; analysis of deformation modes in superplastic Al-base alloys; study of deformation and corrosion in Cu-, Fe-, and Ni-base alloys.

Availability: To experienced electron microscopists having research applications which require high voltage electron microscopy.

Contact: Dr. Bernard J. Hockey, Physical Properties Section, Materials Building, Room A355, Phone 301921-2901.

TRANSMISSION ELECTRON MICROSCOPE, 200 kV

This instrument allows high resolution examination of surface replicas and actual, thin-foil specimens of metals, ceramics, and polymers. Analysis of microstructure and lattice defects in crystalline materials can be made by electron diffraction contrast and selected area electron diffraction. The instrument is also equipped with a dispersive x-ray energy analysis system for elemental analysis. Compared to conventional transmission electron microscopes (100 kV), specimens which are 70% thicker can be examined.

ENVIRONMENTAL FACILITIES

Portable system for field testing of chlorine-polluted water. Detection and calibration unit of CHLORINE FLUX MONITOR at left, reagent supply unit at right.

CHLORINE FLUX MONITOR

This newly developed electrochemical system for measuring traces of chlorine in water is based on the well-known principle that chlorine, chloramines, and hypochlorites will oxidize an iodide to iodine at the proper pH. A motor-driven pump supplies the water sample to the iodine detector cell at a constant flow rate. The cell contains a platinum microelectrode and a reference electrode with a microammeter connected across them. The ammeter reading resulting from the oxidation reaction is displayed or recorded continuously as the monitored signal. A novel feature is the calibration of the amperometric signal, which is accomplished internally by supplying an accurately known amount of iodine generated coulometrically. Capability: The newly developed chlorine flux monitor is capable of measuring chlorine concentrations from 20 parts per million (or higher, but higher concentrations were not tested) down to a fraction of a part per billion. The response is linear over this wide range (four orders of magnitude) with very few possible interferences, such as ozone, MnO, Cr2O,=, Br2, and 12.

Applications: Measurement of total residual chlorine concentrations in waste water, reactor coolant water, power plants, potable water, etc.

Availability: To any qualified researcher whose interests in chlorine measurements parallel those of Dr. George Marinenko and who is willing to collaborate. Literature:

[1] Dimensions NBS, 58, No. 9, 208-209 (1974). [2] Patent Application No. 610711.

[3] G. Marinenko, Fisheries Research Board of Canada (in press).

Contact: Dr. George Marinenko, Research Chemist, Analytical Chemistry Division, Chemistry Building, Room A225, Phone 301-921-2883.

PRECISION

HUMIDITY MEASUREMENT

This facility comprises two precision humidity generators and a gravimetric hygrometer that can be used separately or in combination for calibration, testing, and development of instruments, sensors and devices and for research on the properties of moist gases. The generators produce continuous gas flows of constant moisture content whereas the hygrometer makes accurate humidity measurements.

Capability: Gas flows up to 150 cubic decimetres per minute. Ambient temperatures from +65 to -75°C. Mixing ratios from about 150 to 1 X 50-5 g/kg (1.5 X 105 to 0.01 ppm). Dew point of +65°C to frost point of 100°C. Ambient pressures from atmospheric to 50 mb. Generated moisture contents known to 0.5 percent or better over most of range and to 2 percent at extremes. Measurement accuracy 0.1 percent. New equipment soon operational will provide improved accuracy over wider ranges. Limited capability for response time testing. Data acquisition system available.

Applications: Calibration of dew-point hygrometers, psychrometers, electric hygrometers, infra-red hygrometers, dewcels, coulometric hygrometers; evaluation and testing of such sensors as carbon film, aluminum oxide, crystal array, lithium chloride, barium floride; enhancement of water vapor in air with pressure.

Availability: Facility available for use on tests, research or programs of NBS divisions, other Government agencies, and industrial or scientific laboratories.

Literature:

[1] J. Res. NBS 40, 479 (1948)

[2] NBS Monograph 73 (1964)

[3] ISA Trans. 7 (No. 4), 356-362 (1969)

Contact: Arnold Wexler, Chief, Humidity Section. Physics Building, Room B356, Phone 301-921-2794.

FIRE RESEARCH

FIRE RESEARCH LABORATORY

A special laboratory building for large scale fire experiments has just been completed.

Capability: A major feature of the building is a 60 ft X 120 ft test floor with a 32 ft ceiling height. The test floor is equipped with smoke abatement equipment to meet air pollution regulations, water supplies and floor drains, making it suitable for a variety of fire experiments. A shop for the fabrication of test structures, a conditioning room for the storage of materials and test structures prior to test, an instrument room, and office and service areas complete the building.

The only permanent experimental facility on the test floor is the Fire Research Test Furnace described in detail below. Other test structures and apparatus are erected as needed for specific programs, providing maximum flexibility in space utilization.

The facilities are: A room and corridor facility. This consists of a corridor approximately 50 ft long with two 8 ft by 8 ft rooms opening onto the side wall. Provisions are made for varying the wall and ceiling spacings and controlling draft conditions. The facility can be used for study of the spread of fire through corridors, the movement of smoke and gas through room-corridor systems, the effect of surface finishing materials on fire spread, and related purposes.

A burn room and smoke movement facility. This is a two story masonry structure with controlled ventilation and communication between floors. It can be used to conduct studies of the burning of room furnishings or to study the spread of smoke, gas, and fire through a multi-compartment structure.

A rate of heat release calorimeter. This instrument measures the rate of heat release and the total heat release from a large sample of material when exposed to a controlled energy flux. It is used to measure the energy contribution of materials involved in a building fire.

A research test furnace. This is a medium-sized unit providing conformity with the temperature-time exposure specification of ASTM E119, plus extension to

150%. It will accommodate 30-ton walls or partitions 10 feet long by 8 feet high, 20-ton columns 8 feet high, or 20-ton floor-ceiling assemblies 8 feet by 10 feet. Furnace pressure is controllable between -0.05 and +0.15 in. water to permit study of the effect on fire performance. The furnace can be used for fire endurance tests on structural components such as ducts, dampers, doors, and plumbing systems, on innovative constructions such as double modular walls, and on joints in wall-floor assemblies. Applications: The Fire Research Laboratory provides a location where large scale fire experiments can be carried out under controlled conditions. Space is available for the construction of a variety of experimental installations.

Availability: Available upon request for research experiments for other Government agencies and industrial groups. Available for research programs of industrial Research Associates. Availability of specific facilities is dependent on workload. Literature:

[1] Francis C. W. Fung, Miles R. Suchomel and Philip L. Oglesby, The NBS Program on Corridor Fires, Fire Journal 67, pages 41-48 (May 1973).

[2] W. J. Parker and M. E. Long, Development of a Heat Release Rate Calorimeter at NBS, ASTM STP 502, pages 135-151 (1972). Contact: Mr. J. A. Benjamin, Fire Technology Division, Technology Building, Room B64, Phone 301-9213255.

HIGH PRESSURE FACILITIES

Application: System 1 has been used for ultrasonic measurements on solids and liquids, for electrical resistance measurements, for measurements of crack propagation in glasses and for the study of phase transition. Apparatus requiring electrical leads can be plugged into a receptacle at the inside bottom of the pressure vessel. A total of four leads are available. System II has been used for ultrasonic measurements in liquids and in solids under either hydrostatic or non-hydrostatic conditions. Transducers to detect shear or longitudinal mode properties are mounted on the outside; they use a back plate as acoustic buffer. A back plate with one electrical lead is also available.

Availability: The equipment is available to qualified researchers after an initial training period or with assistance from Section personnel.

Literature: D. L. Decker et al, High-Pressure Calibration, A Critical Review, J. Phys. & Chem. Ref. Data, 1, no. 3, pp. 173-836, 1972.

Contact: Dr. Peter L. M. Heydemann, Chief, Pressure and Vacuum Section, Metrology Building, Room A149, phone 301-921-2121.

HIGH PRESSURE
OPTICAL

FLUORESCENCE SYSTEM

The optical system measures the pressure-dependent Ishift of the sharp fluorescent R,-line of ruby which has been calibrated against the compression of NaCl as the primary standard. The system was developed to measure pressure in the diamond-anvil high pressure cell, but with minor modification can be used in any pressure vessel which has optical access. Capability: Quantitative pressure determinations are made to 300 kbar with an accuracy in the range of 5 percent; qualitative measurements up to the realizable limit of about 500 kbar. Temperature capability to 300°C is also available, but the accuracy in the pressure measurement is significantly reduced at this temperature.

Applications: Characterization of phenomena induced by pressure-such as phase transitions in solids, freezing pressures of liquids, glass transition pressures in vitrified materials, compressibility measurements (in conjunction with x-ray measurement), and pressure distribution in various pressure transmitting media.

Availability: On a selective basis when not required for Crystallography Section programs. The system

must be operated by Section personnel and only work of mutual interest can be unde taken.

Literature:

[1] G. J. Piermarini, S. Block, J. D. Barnett, and R. A. Forman, J. Appl. Phys. 46, 2774 (1975). [2] G. J. Piermarini and S. Block, Rev. Sci. Instr. 46, 33 (1975).

Contact: Dr. G. J. Piermarini, Materials Building, Room B224, Phone 301-921-2950.

Nat. Bur. Stand. (U.S.) 78A, no. 3, 331-353 (May-June 1974).

Contact: John E. McKinney, Bulk Properties Section, Polymer Building, Room B330, Phone 301-921-2116.

HIGH TEMPERATURE FACILITIES

HIGH PRESSURE

PVT DILATOMETER

This PVT (pressure-volume-temperature) apparatus is used to measure the density of liquids and solids (including polymers) with varying temperature and pressure. The method employs pressurized dilatometry in which a dilatometer is placed in a pressure chamber with glass windows. This chamber is, in turn, placed in a liquid thermostat with glass windows which is controlled by a refrigerator and electric heaters. The pressure is generated by a hand pump and may be determined by a bourdon or dead weight piston gage. The sample volume is determined in terms of the relative height of the mercury column of the dilatometer, using a cathetometer. Capability: Temperature range, -40 to 200°C. Constant heating and cooling rates may be selected as low as .05°/hr; pressure range, 800 bar. (This range may be extended to 2 kbar by using a suitable pressure chamber.) A dead weight piston gage is available to maintain constant pressure during, for example, isobaric heating and cooling, and volume creep

measurements.

Applications: Ordinary equilibrium PVT measurements, including phase changes. Non-equilibrium measurements may include influence of temperature and pressure on glass transition and crystal growth mechanisms, glasses formed at constant volume, and volume creep and stress (pressure) relaxation. The densification of polymer glasses at elevated formation pressures gives a higher refractive index which suggests their use as optical lenses.

Availability: By research workers on problems of mutual interest with those of the Bulk Properties Section. Initial instruction will be given by the Section staff.

Literature:

[1] J. E. McKinney and R. W. Penn, Rev. Sci. Instr. 43, 1212;

[2] J. E. McKinney and M. Goldstein, J. Res.,

Levitation vacuum melting equipment for preparation of high-purity materials in the ALLOY PREPARATION LABORATORY.

ALLOY PREPARATION
LABORATORY

Research grade samples of metals and alloys are prepared when such samples are not readily available commercially, or when accurate details are required concerning the purity of the constituents and the melting and fabricating history.

Capability: Vacuum-induction melting and casting; arc furnace; levitation melting furnace; electronbeam zone refiner; electron-beam button melter; electron-beam evaporator; induction and resistance melting and casting furnaces; heat-treating furnaces; cold-working equipment for rolling, swaging, and drawing; apparatus for producing metallic hydrides under hydrogen pressures up to 6900 kN/m2 (1000 psi).

Applications: High purity iron ingot with 1.194 ±0.004% carbon; homogeneous ingot of magnesium-zinc; 200-mesh lead-indium powders; devices for hydrogen storage.