Abstract: During the emission-spectroscopical testing of metallic samples by means of unipolar discharges, material is precipitated onto the counterelectrode material which leads to faulty test results. According to the invention, at the start of the pre-spark period half waves of the unipolar discharge are replaced by oscillating discharges, wherein two parallel-connected discharge capacitors and two series-connected discharge resistors, one discharge capacitor and one discharge resistor can be shunted and the shunting is canceled out after a prespecified period of time, starting with the pre-spark period.

Abstract: The determination, through spectrographic analysis, of the C content of iron and steel alloy workpieces via the C 1931.02 line is made using spectrometers having a test head that can be attached to the workpiece. The region of the discharge near the surface of the workpiece is isolated in an argon atmosphere from the light path of the discharge to be imaged onto the grating, so that the two unwanted iron lines, the Fe 1931.4 and the Fe 1930.8 lines, do not occur in the grating spectrum.

Abstract: An arrangement of the Rowland character includes a support and a concave grating on the support for producing the spectrum characteristic of a sample being investigated. The support has a series of slits thereon which are positioned on the Rowland circle and are adjusted to the spectral lines of samples to be investigated. An element on the support is provided with a primary slit for directing the radiation derived from a sample being investigated onto the concave grating. The primary slit is positioned on the Rowland circle and the element provided with the primary slit is mounted on the support for movement along the arc of the Rowland circle. The element is mounted in such a manner as to be arrestable in a plurality of positions. The element is favorably in the form of a plate.

Abstract: A workpiece is positioned in contact with a contact electrode and spaced by a gap from a counter electrode. A unipolar electrical pulse is passed across this gap during a first time period. Thereafter during a second time period the light from the spark drawn across the gap is diffracted into a spectrum having lines corresponding to a plurality of the components of the workpiece and these lines are transformed into respective electrical signals having intensities corresponding to the concentrations of the respective components in the workpiece. During this second period the pulse continues to pass across the gap and the signals are integrated. At the start of a third period the pulse is stopped and then the integrated signals are compared with respective reference signals and error signals are generated in the case of any variance between the two.

Abstract: An electrode for a spectro-analytical arrangement is of a substance consisting of carbonaceous and metallic components so that an envelope of reducing atmosphere surrounds an electric spark discharge generated between an electrode and a metallic body the composition of the material of which is to be spectro-analytically determined. The substance may be a homogeneous mixture of the carbonaceous and metallic components, such as a sintered mixture of pulverulant metallic and carbonaceous metals. The particles of the metallic component have sizes of at most 0.1 millimeter, while the particles of the carbonaceous component have sizes at most 0.01 millimeter. The carbonaceous component may be graphite, while the metallic component may be silver. The amount of graphite in the substance may be between 5 and 20% by weight and the amount of silver may be between 95 and 80% by weight. The preferred use of the electrode of the invention is in a spectral quantometer.

Abstract: An arrangement of the Rowland character includes a support and a concave grating on the support for producing the spectrum characteristic of a sample being investigated. The support has a series of slits thereon which are positioned on the Rowland circle and are adjusted to the spectral lines of samples to be investigated. An element on the support is provided with a primary slit for directing the radiation derived from a sample being investigated onto the concave grating. The primary slit is positioned on the Rowland circle and the element provided with the primary slit is mounted on the support for movement along the arc of the Rowland circle. The element is mounted in such a manner as to be arrestable in a plurality of positions. The element is favorably in the form of a plate.

Abstract: An alloy to be tested is formed of a basis metal and a plurality of alloying elements. A diffraction spectrum having lines corresponding to the basis metal and to each of the alloying elements is generated from the alloy by sparking and electrical signals each having an intensity proportional to the intensity of a respective one of the lines of the spectrum are formed. Each of these signals is integrated and the integrated signals corresponding to lines of the alloy elements are each compared with the integrated signal corresponding to the line of the basis metal and difference signals are generated. These difference signals are evaluated by being passed through a threshold circuit which sounds an alarm when they lie outside a predetermined range.

Abstract: A spark discharge test apparatus has a holder electrode conductively engageable with a workpiece, a counter electrode adapted to be spaced by a gap from the workpiece while it is in contact with the holder electrode, a power supply including a closable switch and connected across the electrode for passing a unipolar electrical pulse across the gap only when the switch is closed, and a circuit including a terminal connectable to the workpiece and connected so as to close the switch allowing operation of the power supply only on detection of a closed circuit between the terminal and the holder electrode. Thus, a unipolar electrical pulse can only be fired between the counter electrode and the workpiece when the workpiece is in good electrical contact with the holder electrode. This safety circuit comprises a low-voltage relay having one side connected to a low-voltage power supply and another side connected to the terminal.

Abstract: An apparatus for spectroscopically analyzing the composition of a workpiece comprises a support on which is mounted a sleeve having an open end engageable with the surface of the workpiece and formed with a laterally open cutout. An electrode is mounted on the support and has an electrode tip limitedly displaceable in the sleeve adjacent the open end thereof. A laterally extending screw is engaged between an insulating tube constituting part of the support and the electrode and serves to fix the electrode in the sleeve with the electrode tip spaced inwardly of the open end of the sleeve. A power supply is connected to the electrode for sparking between the surface of the workpiece and the tip when the two are spaced apart and the open end of the sleeve abuts the surface.