Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/20—Metals
  • G01N33/205—Metals in liquid state, e.g. molten metals

Definitions

• the method is used to determine the element concentration in electron beam melting in order to measure continuously during the melting process and thus to provide the possibility of an immediate correction.
• the method is used in the melting of alloys.
• the electron beam regime is often designed in such a way that the observation field of the X-ray spectrometer is only briefly touched by the point of impact of the electron beam (spot).
• the X-rays which are measured during the time when the observation location is not in the spot, are generated by scattered electrons. This can lead to measurement errors.
• the invention has for its object to provide a method for determining the element concentration in-situ when melting with an electron beam, which provides an accurate measurement result for a short time. It must be usable under industrial conditions and may not require a significantly higher effort than the known methods.
• the method is to be based on the principle of evaluating the X-ray radiation produced during melting.
• this object is achieved by evaluating the characteristic X-ray radiation of the elements contained in the melt by detection with an X-ray spectrometer in that special measuring phases are integrated into the melting process of the electron beam at certain predetermined time intervals in the melting process. An X-ray analytical determination of the concentration takes place only in these time intervals. This means that during the time of the measured value acquisition the melting regime is modified in such a way that no vapor cloud influencing the measurement arises over the melt.
• the acceleration voltage and / or power and / or deflection of the electron beam different from that for the To change the required parameters of the melting process.
• the power density distribution on the melt bath is to be changed so that the vapor pressure is reduced.
• the acceleration voltage of the electron beam is too high for X-ray analysis in many cases.
• the observation field for the X-ray analytical concentration determination then lies in the area of this area.
• the electron beam strikes this small area according to a program adapted to the melting technology and generates the corresponding deflection pattern. This ensures that the electron beam touches the observation location of the spectrometer during the measurement phase and that optimal measurement conditions are given.
• the molten bath surface 1 in the crystallizer 2 is acted upon by the electron beam according to technologically intended patterns. These can be circular deflection patterns 3 distributed over the surface.
• the electron beam is directed into the center of the molten bath surface 1 over a constant time, the so-called measurement phase, and acts on a field 4 there in a grid with reduced power.
• This field 4 on the molten bath surface has the ratio very small extensions to the entire melt pool surface.
• the observation field 5 of the x-ray spectrometer known per se is located in this field 4.
• the electron beam is again programmed on the molten bath surface 1. miert deflected to continue the melting process.
• the element concentration is determined by detecting the X-ray radiation generated with the electron beam in the region of the observation field 5.
• the intensity of the characteristic radiation of the element to be determined and the intensity of a further part from the X-ray spectrum are measured from the same location of the observation field 5.
• the quotient which is a function of the concentration of the element to be determined, is formed from the two measured variables.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Medicinal Chemistry (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Recrystallisation Techniques (AREA)

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Publications (1)

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Citations (1)

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• 1992
  • 1992-03-19 DE DE4208955A patent/DE4208955C1/de not_active Expired - Fee Related
• 1993
  • 1993-03-03 WO PCT/DE1993/000203 patent/WO1993019360A1/de not_active Ceased
  • 1993-03-03 AT AT93905160T patent/ATE154703T1/de not_active IP Right Cessation
  • 1993-03-03 JP JP5516156A patent/JPH07506901A/ja active Pending
  • 1993-03-03 EP EP93905160A patent/EP0631666B1/de not_active Expired - Lifetime
  • 1993-03-03 DE DE59306792T patent/DE59306792D1/de not_active Expired - Fee Related

Patent Citations (1)

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