DE69617086D1 - Verfahren zum Ausbessern metallischer Einkristallgegenstände - Google Patents

Verfahren zum Ausbessern metallischer Einkristallgegenstände

Info

Publication number
DE69617086D1
DE69617086D1 DE69617086T DE69617086T DE69617086D1 DE 69617086 D1 DE69617086 D1 DE 69617086D1 DE 69617086 T DE69617086 T DE 69617086T DE 69617086 T DE69617086 T DE 69617086T DE 69617086 D1 DE69617086 D1 DE 69617086D1
Authority
DE
Germany
Prior art keywords
single crystal
metallic single
crystal objects
repairing metallic
repairing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
DE69617086T
Other languages
English (en)
Other versions
DE69617086T2 (de
Inventor
Marcin, Jr
Justin Andrea Neutra
David Henry Abbott
James Peter Aduskevich
Dilip M Shah
Dorothea Nadette Carraway
Raymond Paul Langevin
Marc R Sauerhoffer
Richard Alan Stone
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Raytheon Technologies Corp
Original Assignee
United Technologies Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United Technologies Corp filed Critical United Technologies Corp
Application granted granted Critical
Publication of DE69617086D1 publication Critical patent/DE69617086D1/de
Publication of DE69617086T2 publication Critical patent/DE69617086T2/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P6/00—Restoring or reconditioning objects
    • B23P6/002—Repairing turbine components, e.g. moving or stationary blades, rotors
    • B23P6/007—Repairing turbine components, e.g. moving or stationary blades, rotors using only additive methods, e.g. build-up welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20—Bonding
    • B23K26/32—Bonding taking account of the properties of the material involved
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/34—Laser welding for purposes other than joining
    • B23K26/342—Build-up welding
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/005—Repairing methods or devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/001—Turbines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/18—Dissimilar materials
    • B23K2103/26—Alloys of Nickel and Cobalt and Chromium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Laser Beam Processing (AREA)
DE69617086T 1995-05-01 1996-04-25 Verfahren zum Ausbessern metallischer Einkristallgegenstände Expired - Lifetime DE69617086T2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43181495A 1995-05-01 1995-05-01
US08/620,588 US5914059A (en) 1995-05-01 1996-03-22 Method of repairing metallic articles by energy beam deposition with reduced power density

Publications (2)

Publication Number Publication Date
DE69617086D1 true DE69617086D1 (de) 2002-01-03
DE69617086T2 DE69617086T2 (de) 2002-04-18

Family

ID=27029218

Family Applications (1)

Application Number Title Priority Date Filing Date
DE69617086T Expired - Lifetime DE69617086T2 (de) 1995-05-01 1996-04-25 Verfahren zum Ausbessern metallischer Einkristallgegenstände

Country Status (5)

Country Link
US (1) US5914059A (de)
EP (1) EP0740976B1 (de)
JP (1) JP4094690B2 (de)
DE (1) DE69617086T2 (de)
TW (1) TW326009B (de)

Families Citing this family (72)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6615470B2 (en) * 1997-12-15 2003-09-09 General Electric Company System and method for repairing cast articles
US6217286B1 (en) * 1998-06-26 2001-04-17 General Electric Company Unidirectionally solidified cast article and method of making
US6326585B1 (en) 1998-07-14 2001-12-04 General Electric Company Apparatus for laser twist weld of compressor blisks airfoils
US6172327B1 (en) * 1998-07-14 2001-01-09 General Electric Company Method for laser twist welding of compressor blisk airfoils
US6054672A (en) * 1998-09-15 2000-04-25 Chromalloy Gas Turbine Corporation Laser welding superalloy articles
DE59909337D1 (de) * 1999-06-03 2004-06-03 Alstom Technology Ltd Baden Verfahren zur Herstellung oder zur Reparatur von Kühlkanälen in einstristallinen Komponenten von Gasturbinen
DE19934856A1 (de) * 1999-07-24 2001-01-25 Abb Research Ltd Turbinenschaufel und Verfahren zu deren Herstellung
US6199746B1 (en) * 1999-08-02 2001-03-13 General Electric Company Method for preparing superalloy castings using a metallurgically bonded tapered plug
KR20010078305A (ko) * 2000-02-07 2001-08-20 제이 엘. 차스킨, 버나드 스나이더, 아더엠. 킹 클래딩 또는 용접 속도를 증가시키는 방법 및 장치
US6521861B2 (en) 2000-02-07 2003-02-18 General Electric Company Method and apparatus for increasing welding rate for high aspect ratio welds
US6333484B1 (en) 2000-03-17 2001-12-25 Chromalloy Gas Turbine Corporation Welding superalloy articles
US6784085B2 (en) * 2000-11-30 2004-08-31 North Carolina State University MIIIN based materials and methods and apparatus for producing same
US6495793B2 (en) 2001-04-12 2002-12-17 General Electric Company Laser repair method for nickel base superalloys with high gamma prime content
US6489584B1 (en) * 2001-05-08 2002-12-03 General Electric Company Room-temperature surface weld repair of nickel-base superalloys having a nil-ductility range
EP1312437A1 (de) * 2001-11-19 2003-05-21 ALSTOM (Switzerland) Ltd Verfahren zum Reparieren eines Risses
EP1340583A1 (de) * 2002-02-20 2003-09-03 ALSTOM (Switzerland) Ltd Verfahren zum Umschmelzen bzw. Auftragschweissen mittels Laser
EP1340567A1 (de) * 2002-02-27 2003-09-03 ALSTOM (Switzerland) Ltd Verfahren zum Entfernen von Gussfehlern
US7295691B2 (en) * 2002-05-15 2007-11-13 Ge Medical Systems Global Technology Company, Llc Computer aided diagnosis of an image set
EP1396556A1 (de) * 2002-09-06 2004-03-10 ALSTOM (Switzerland) Ltd Verfahren zum Regeln der Mikrostruktur einer mittels Laserschichten hergestellten Hartschicht
EP1447457A1 (de) * 2003-02-17 2004-08-18 ALSTOM Technology Ltd Verfahren zur Verstärkung der Korngrenzen einer Komponente aus Ni-basierter Superlegierung
US7009137B2 (en) * 2003-03-27 2006-03-07 Honeywell International, Inc. Laser powder fusion repair of Z-notches with nickel based superalloy powder
DE10344225A1 (de) * 2003-09-24 2005-04-21 Mtu Aero Engines Gmbh Verfahren und Vorrichtung zum Schweißen von Bauteilen
JP4551082B2 (ja) 2003-11-21 2010-09-22 三菱重工業株式会社 溶接方法
EP1561536A1 (de) * 2004-02-03 2005-08-10 Siemens Aktiengesellschaft Reparatur-Lotverfahren zum Reparieren eines Bauteils, welches ein Basismaterial mit einer gerichteten Mikrostruktur umfasst
US20050178750A1 (en) * 2004-02-13 2005-08-18 Kenny Cheng Repair of article by laser cladding
US6972390B2 (en) * 2004-03-04 2005-12-06 Honeywell International, Inc. Multi-laser beam welding high strength superalloys
US20050274701A1 (en) * 2004-06-10 2005-12-15 United Technologies Corporation Homogeneous welding via pre-heating for high strength superalloy joining and material deposition
US6872912B1 (en) 2004-07-12 2005-03-29 Chromalloy Gas Turbine Corporation Welding single crystal articles
FR2874624B1 (fr) 2004-08-30 2007-04-20 Snecma Moteurs Sa Procede de rechargement d'une piece metallique monocristalline ou a solidification dirigee.
GB0420578D0 (en) * 2004-09-16 2004-10-20 Rolls Royce Plc Forming structures by laser deposition
DE602006000955T2 (de) * 2005-02-25 2009-05-28 Snecma Verfahren zur mechanischen Charakterisierung eines metallischen Materials
US20060219758A1 (en) * 2005-03-29 2006-10-05 Siemens Westinghouse Power Corporation Welding of gamma'-strengthened superalloys
US7094988B1 (en) 2005-04-18 2006-08-22 Honeywell International, Inc. Laser welding heat treat process
US20060231535A1 (en) * 2005-04-19 2006-10-19 Fuesting Timothy P Method of welding a gamma-prime precipitate strengthened material
JP5061836B2 (ja) * 2007-10-10 2012-10-31 株式会社日立プラントテクノロジー 羽根車の溶接方法及び羽根車
JP4818297B2 (ja) * 2008-03-19 2011-11-16 株式会社東芝 ガスタービン部品の補修方法及びガスタービン部品
DE102008019636A1 (de) * 2008-04-18 2009-10-22 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Bauteil mit Schweißnaht und Verfahren zur Herstellung einer Schweißnaht
DE102008058140A1 (de) * 2008-11-20 2010-05-27 Mtu Aero Engines Gmbh Verfahren zur Reparatur von einkristallinen Turbinenschaufeln
US8373089B2 (en) * 2009-08-31 2013-02-12 General Electric Company Combustion cap effusion plate laser weld repair
US8726501B2 (en) * 2009-08-31 2014-05-20 General Electric Company Method of welding single crystal turbine blade tips with an oxidation-resistant filler material
JP5377241B2 (ja) * 2009-11-20 2013-12-25 株式会社東芝 ガスタービン動翼の補修方法およびガスタービン動翼
DE102010001414B4 (de) * 2010-02-01 2013-05-08 Rolls-Royce Deutschland Ltd & Co Kg Verfahren zur Reparatur von Labyrinth-Dichtungsstegen
US8618434B2 (en) * 2010-03-22 2013-12-31 Siemens Energy, Inc. Superalloy repair welding using multiple alloy powders
JP2011212730A (ja) 2010-04-01 2011-10-27 Hitachi Ltd 肉盛溶接方法およびレーザ肉盛溶接装置
CH705662A1 (de) * 2011-11-04 2013-05-15 Alstom Technology Ltd Prozess zur Herstellung von Gegenständen aus einer durch Gamma-Prime-Ausscheidung verfestigten Superlegierung auf Nickelbasis durch selektives Laserschmelzen (SLM).
US10415390B2 (en) * 2012-05-11 2019-09-17 Siemens Energy, Inc. Repair of directionally solidified alloys
US9144822B2 (en) 2012-09-28 2015-09-29 General Electric Company Methods and systems for joining materials
US10293437B2 (en) * 2012-10-12 2019-05-21 United Technologies Corporation Method of working a gas turbine engine airfoil
EP2735399A1 (de) * 2012-11-23 2014-05-28 Siemens Aktiengesellschaft Bestimmung der Verfahrrichtung bei der Schweißung eines gerichtet erstarrten Werkstoffs
US20140178600A1 (en) * 2012-12-21 2014-06-26 Shenzhen China Star Optoelectronics Technology Co., Ltd. Coating method and device
US10315275B2 (en) * 2013-01-24 2019-06-11 Wisconsin Alumni Research Foundation Reducing surface asperities
US9476304B2 (en) * 2013-05-10 2016-10-25 Caterpillar Inc. Laser casting blade repair
US20150132143A1 (en) * 2013-11-11 2015-05-14 Gerald J. Bruck Welding process and reduced restraint weld joint
US10532556B2 (en) 2013-12-16 2020-01-14 General Electric Company Control of solidification in laser powder bed fusion additive manufacturing using a diode laser fiber array
US10328685B2 (en) 2013-12-16 2019-06-25 General Electric Company Diode laser fiber array for powder bed fabrication or repair
JP6104840B2 (ja) * 2013-12-17 2017-03-29 株式会社東芝 タービン部品及びタービン部品の肉盛方法
JP6015709B2 (ja) * 2014-05-14 2016-10-26 トヨタ自動車株式会社 肉盛加工における粉体供給方法
US9527165B2 (en) 2015-02-05 2016-12-27 Siemens Energy, Inc. Powder deposition process utilizing vibratory mechanical energy
US20160375522A1 (en) * 2015-06-26 2016-12-29 Siemens Energy, Inc. Welding method for superalloys
DE102015219513B4 (de) * 2015-10-08 2022-05-05 MTU Aero Engines AG Reparaturverfahren für Dichtsegmente
FR3046740B1 (fr) * 2016-01-18 2018-05-25 Safran Aircraft Engines Procede de rechargement ou de fabrication d'une piece metallique
JP6553102B2 (ja) * 2016-02-03 2019-07-31 ゼネラル・エレクトリック・カンパニイ ダイオードレーザファイバーアレイを用いたレーザ粉体床溶融結合付加製造における凝固制御法
EP3321004A1 (de) * 2016-11-14 2018-05-16 SLM Solutions Group AG Verfahren, verwendung und vorrichtung zur herstellung eines einkristallinen werkstücks
US11203066B2 (en) 2016-11-16 2021-12-21 Cummins Inc. Systems and methods for adding material to castings
DE102017201261A1 (de) 2017-01-26 2018-07-26 Siemens Aktiengesellschaft Auftragschweißvorrichtung mit magnetischer Beeinflussung und Verfahren zum Auftragschweißen
WO2019014445A1 (en) * 2017-07-12 2019-01-17 General Electric Company METHOD FOR REPAIRING AN ARTICLE AND RELATED ARTICLE
JP6792874B2 (ja) * 2017-09-11 2020-12-02 国立大学法人大阪大学 溶接方法及び溶接装置
US10486272B2 (en) 2018-03-06 2019-11-26 General Electric Company Turbine blade tip rail formation and repair using laser welding
US11135677B2 (en) * 2018-03-06 2021-10-05 General Electric Company Laser welding of component
JP7067134B2 (ja) * 2018-03-07 2022-05-16 株式会社ジェイテクト 積層造形装置の造形方法及び積層造形装置
WO2020150309A1 (en) 2019-01-16 2020-07-23 Magna International Inc. Method of removal of heat checking
RU2740687C2 (ru) * 2019-05-24 2021-01-19 Федеральное государственное бюджетное образовательное учреждение высшего образования "Казанский национальный исследовательский технический университет им. А.Н. Туполева-КАИ" (КНИТУ-КАИ) Способ восстановления изделия лазерно-акустической наплавкой и устройство для его осуществления

Family Cites Families (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7216832A (de) * 1972-12-12 1974-06-14
US4028787A (en) * 1975-09-15 1977-06-14 Cretella Salvatore Refurbished turbine vanes and method of refurbishment thereof
CA1095387A (en) * 1976-02-17 1981-02-10 Conrad M. Banas Skin melting
GB2052566B (en) * 1979-03-30 1982-12-15 Rolls Royce Laser aplication of hard surface alloy
US4323756A (en) * 1979-10-29 1982-04-06 United Technologies Corporation Method for fabricating articles by sequential layer deposition
US4382169A (en) * 1981-03-24 1983-05-03 Rabkin Daniil M Weld deposition of metal other than aluminium onto aluminium-base alloy
IT1179061B (it) * 1984-08-20 1987-09-16 Fiat Auto Spa Procedimento per l'effettuazione di un trattamento su pezzi metallici con l'aggiunta di un materiale d'apporto e con l'impiego di un laser di potenza
US4743733A (en) * 1984-10-01 1988-05-10 General Electric Company Method and apparatus for repairing metal in an article
US4944817A (en) * 1986-10-17 1990-07-31 Board Of Regents, The University Of Texas System Multiple material systems for selective beam sintering
US4927992A (en) * 1987-03-04 1990-05-22 Westinghouse Electric Corp. Energy beam casting of metal articles
US4804815A (en) * 1987-06-01 1989-02-14 Quantum Laser Corporation Process for welding nickel-based superalloys
US4878953A (en) * 1988-01-13 1989-11-07 Metallurgical Industries, Inc. Method of refurbishing cast gas turbine engine components and refurbished component
US5273204A (en) * 1988-03-25 1993-12-28 Howmet Corporation Method for joining materials by metal spraying
US4940390A (en) * 1988-05-05 1990-07-10 Westinghouse Electric Corp. Turbine system having more failure resistant rotors and repair welding of low alloy ferrous turbine components by controlled weld build-up
US5038014A (en) * 1989-02-08 1991-08-06 General Electric Company Fabrication of components by layered deposition
US5135695A (en) * 1989-12-04 1992-08-04 Board Of Regents The University Of Texas System Positioning, focusing and monitoring of gas phase selective beam deposition
DE59006143D1 (de) * 1989-12-27 1994-07-21 Sulzer Ag Vorrichtung zum Schweissen und/oder Beschichten von Werkstücken, Düse für eine derartige Vorrichtung sowie Manipulator für die Düse einer derartigen Vorrichtung.
JP2890658B2 (ja) * 1990-04-23 1999-05-17 いすゞ自動車株式会社 アルミ鋳物部品の局部強化方法
JPH04120259A (ja) * 1990-09-10 1992-04-21 Agency Of Ind Science & Technol レーザ溶射法による機器・部材の製造方法および装置
US5113582A (en) * 1990-11-13 1992-05-19 General Electric Company Method for making a gas turbine engine component
DE4039807C1 (de) * 1990-12-13 1991-10-02 Mtu Muenchen Gmbh
US5160822A (en) * 1991-05-14 1992-11-03 General Electric Company Method for depositing material on the tip of a gas turbine engine airfoil using linear translational welding
US5312584A (en) * 1992-02-18 1994-05-17 General Motors Corporation Moldless/coreless single crystal castings of nickel-aluminide
DE59208497D1 (de) * 1992-03-02 1997-06-19 Sulzer Innotec Ag Freiformschweissen von Metallstrukturen mit Laser
US5291937A (en) * 1992-07-30 1994-03-08 General Electric Company Method for providing an extension on an end of an article having internal passageways
US5554837A (en) * 1993-09-03 1996-09-10 Chromalloy Gas Turbine Corporation Interactive laser welding at elevated temperatures of superalloy articles
US5393482A (en) * 1993-10-20 1995-02-28 United Technologies Corporation Method for performing multiple beam laser sintering employing focussed and defocussed laser beams

Also Published As

Publication number Publication date
TW326009B (en) 1998-02-01
US5914059A (en) 1999-06-22
DE69617086T2 (de) 2002-04-18
EP0740976A1 (de) 1996-11-06
JPH09110596A (ja) 1997-04-28
EP0740976B1 (de) 2001-11-21
JP4094690B2 (ja) 2008-06-04

Similar Documents

Publication Publication Date Title
DE69617086D1 (de) Verfahren zum Ausbessern metallischer Einkristallgegenstände
DE69514809T2 (de) Verfahren zum reparieren von substraten
DE69325218D1 (de) Verfahren zum wiederentbindbaren metallischen Verbinden
DE69501010T2 (de) Verfahren zum Beschichten metallischer Oberflächen
DE69311252D1 (de) Verfahren zum Biegen von metallischen Rohren
DE69302420D1 (de) Verfahren zum Fotoformen
DE69432135T2 (de) Verfahren zum Luftreifensentwurf
DE69519733T2 (de) Verfahren zum zerkleinern von hydroxypropylmethylcellulose
DE19681602T1 (de) Verfahren zum Entfernen von Metall
DE69516118T2 (de) Verfahren zum superplastischen Strangpressen
DE59607837D1 (de) Verfahren zum kontinuierlichen ersintern eines granulats
ATE243789T1 (de) Enzymatisches verfahren zum färben
DE59502479D1 (de) Verfahren zum Umformen von Metallblech
DE69624783D1 (de) Verfahren zum vakuumfeinen von stahlschmelze
DE69602398T2 (de) Verfahren zum Flüssigkeitstransport
DE59604614D1 (de) Verfahren zum ausbessern von beschichtungsfehlern
DE69606131T2 (de) Kontinuierliches Verfahren zum Umhüllen von Gegenständen
ATA66195A (de) Verfahren zum herstellen von gehäusen
DE69608652T2 (de) Verfahren zum Aufkohlen von Metallen
DE59601365D1 (de) Verfahren zum Isolieren von Formspulen
DE59601684D1 (de) Verfahren zum Recyclen von Diaphragmen
DE59402842D1 (de) Verfahren zum schweissen
DE69423681T2 (de) Verfahren zum Härten von metallischen Gegenstanden
DE59604977D1 (de) Verfahren zum Recycling von Feuerfestmaterial
DE69626460D1 (de) Verfahren zum Elektroplattieren

Legal Events

Date Code Title Description
8364 No opposition during term of opposition