Abstract: A chemically processed steel sheet comprises a steel base coated with an Al-Si alloy plating layer, whose Si content is preferably adjusted to 5-13 mass % as a whole and to 7-80 mass % at a surface, and a converted layer generated on the surface of the plating layer. The converted layer contains both of soluble and scarcely-soluble compounds. The soluble compound such as a manganese oxide or hydroxide or a valve metal fluoride is once dissolved to water in an atmosphere and then re-precipitated as scarcely-soluble compounds at defective parts of the converted layer. The scarcely-soluble compounds act as a barrier for corrosion-prevention of a base steel. Due to the re-precipitation, i.e. self-repairing faculty, excellent corrosion resistance of the converted layer is still maintained even after defects are introduced therein during plastic deformation of the steel sheet.

Abstract: In a chromating solution comprising a water-soluble chromium compound and a reducing agent and in which hexavalent chromium ions produced by dissolution of the water-soluble chromium compound have been partly reduced with the reducing agent to trivalent chromium ions, an oxycarboxylic acid compound is used as the reducing agent. This chromating solution causes neither gelation nor sedimentation of the solution even when hexavalent chromium ions are reduced to trivalent chromium ions at a reduction percentage of more than 50%. The chromating solution and a chromate film formed on a steel sheet may also contain an organic resin, phosphoric acid or a phosphoric acid compound, or a silica sol.

Abstract: In a chromating solution comprising a water-soluble chromium compound and a reducing agent and in which hexavalent chromium ions produced by dissolution of the water-soluble chromium compound have been partly reduced with the reducing agent to trivalent chromium ions, an oxycarboxylic acid compound is used as the reducing agent.

Abstract: In a chromating solution comprising a water-soluble chromium compound and a reducing agent and in which hexavalent chromium ions produced by dissolution of the water-soluble chromium compound have been partly reduced with the reducing agent to trivalent chromium ions, an oxycarboxylic acid compound is used as the reducing agent. This chromating solution causes neither gelation nor sedimentation of the solution even when hexavalent chromium ions are reduced to trivalent chromium ions at a reduction percentage of more than 50%. The chromating solution and a chromate film formed on a steel sheet may also contain an organic resin, phosphoric acid or a phosphoric acid compound, or a silica sol.

Abstract: The invention provides a horizontal synchronizing signal frequency measuring instrument which can measure a horizontal synchronizing signal frequency with a higher degree of accuracy. The horizontal synchronizing signal frequency measuring instrument includes a first counter for counting a reference clock signal, a second counter of the preset type for counting a horizontal synchronizing signal, and a control section operable to detect an edge of the vertical synchronizing signal, set a first preset value to the second counter, detect that a count value of pulses by the second counter reaches a first preset value, renders a count control signal active, reset and start the first and second counters, detect that the count value by the second counter reaches the second preset value, render the count control signal inactive and calculate a frequency of the horizontal synchronizing signal from the count value of the first counter, the second preset value and a frequency of the reference clock signal.