Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
  • C23C30/005—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process on hard metal substrates

Definitions

• the present invention relates to coated cemented carbide inserts with improved cutting properties being obtained as a result of modifications of the chemical and mechanical properties of the binder phase.
• Cemented carbide grades for metal cutting applica ⁇ tions generally contain WC, ⁇ -phase (a solid solution of generally TiC, NbC, TaC and WC) and binder phase, gene- rally cobalt. Their properties are optimized by varying the WC grain size, volume fraction of the binder phase and/or the ⁇ -phase and by optimising the carbon content.
• ⁇ -phase a solid solution of generally TiC, NbC, TaC and WC
• binder phase gene- rally cobalt.
• Their properties are optimized by varying the WC grain size, volume fraction of the binder phase and/or the ⁇ -phase and by optimising the carbon content.
• One recent major improvement of the properties of coated cemented carbide is the introduction of binder phase en- riched surface zones.
• two major groups of coated cemented carbide inserts for metal cutting are used today: one with even distribution of binder phase within the whole insert and one with binder phase enriched surface zones.
• the cemented carbides with binder phase enriched surface zones are mainly found in ⁇ -phase containing grades whereas straight WC-Co grades have even binder phase distribution without said binder phase enrichment.
• the binder phase is based on cobalt containing varying amounts of tungsten and carbon in solid solution. In addition to tungsten or carbon, only very low contents of other ele ⁇ ments (mainly impurities) are present in the binder phase. In applications in highly corrosive environments e.g.
• binder phase alloys based on Co-Ni-Cr or Ni-Cr are used e.g. such as disclosed in EP-A-28620.
• the invention relates to a coated cemented carbide for metal cutting applications.
• Said cemented carbide contains 3-20 weight-%, preferably 4-14 weight-% binder phase comprising in solid solution in weight-%: Co max 95, Ni max 95, Cr 3-25, preferably 5-15, and, optional ⁇ ly, W max 30, Mo max 15, Al max 2 and Fe max 70.
• the binder phase comprises in solid solution in weight-%: Co 20-80, Mo 1-6, pre- ferably about 2, Cr 3-15, preferably about 10 and rest Ni. V may be added up to 5 weight-%, preferably between 1 and 3 weight-%.
• the binder phase is nickel based and comprises in solid solution , in weight-%: Co max 30, Mo 1-6 and Cr 3-15.
• the Co:Ni weight ra ⁇ tio in the binder phase is about 1:1 or about 3:1.
• the carbon content should be between a lower value corresponding to the ⁇ -phase limit and an upper value corresponding to the stoichiometric carbon content.
• the carbon content can be below the ⁇ -phase limit and thus the cemented carbide will contain also ⁇ -phase or other substoichiometric phases. 1-20 volume-% has been found suitable, preferably 3-10 vo- lume-%.
• the invention can be applied to inserts with even distribution of binder phase or, preferably, to inserts with a binder phase enriched surface zone up to 50 ⁇ m, preferably between 10 and 25 ⁇ thick.
• the degree of the binder phase enrichment shall be between 1.2 and 2.5 times, preferably between 1.4 and 1.8, higher than the binder phase content of the rest of the insert.
• Such in ⁇ serts can be made e.g. using the technique disclosed in US 4,610,931.
• the cemented carbide is coated with wear resistant layers as known in the art using known CVD, MTCVD or PVD technique.
• MTCVD is a moderate temperature CVD-process using e.g. CH3CN gas and TiCl . If the total nickel con ⁇ tent is more than about 1.5 weight-% care has to be ta- ken to avoid the detrimental effects of nickel on the coating quality e.g. by using at least at the beginning of the coating process a rather low temperature, pre ⁇ ferably ⁇ 960 °C.
• Coatings comprising carbides and/or carbonitrides and/or oxicarbides and/or oxinitrides and/or oxicarbo- nitrides of titanium and/or AI2O3 are particularly use ⁇ ful.
• at least one 0.3-5 ⁇ , preferably 0.5-1.5 ⁇ m, interlayer comprising Ti(C,0) or Ti(C,0,N) or Ti(N,0) is deposited within a part of the coating containing titanium about 0.5-3 ⁇ m from the ce ⁇ mented carbide surface such as disclosed in Swedish Pa ⁇ tent Application 9400951-1.
• the coating thickness shall be ⁇ 30 ⁇ m, preferably 3- 16 ⁇ m.
• the total coating thick- ness should be 3-7 ⁇ m and for turning applications the total coating thickness should be 5-16 ⁇ m.
• the present invention is particularly useful in ma ⁇ chining of steel and cast iron when the cutting inserts are subjected to thermal and mechanical fatigue condi- tions. This is typical for milling operations but some- times it also occurs in certain turning operations with intermittent character.
• the invention has been described with reference to cutting tool inserts of cemented carbide. It is obvious that the invention can be applied to coated cutting tool insert for metal cutting applications containing at least one hard constituent of a carbide, nitride and/or carbonitride of the metals Ti, Ta, Hf, Nb, V, Zr and W or solid solutions thereof in a binder phase.
• Cutting tool inserts according to the invention with the following composition in weight-%: 91.5 WC, 3.9 Co, 3.7 Ni, 0.8 Cr, 0.1 Mo were prepared and coated with a coating consisting of 0.5 ⁇ m TiN, 5 ⁇ m Ti(C,N) and 3 ⁇ m AI2O3.
• the TiN layer was the inner layer closest to the cemented carbide and it was deposited at a temperature of 920 °C.
• the Ti(C,N) layer was deposited using MTCVD technique.
• inserts with the composition in weight-%: 91.5 WC and 8.5 Co and provided with the same coating were used.
• Tool life criterion Edge frittering of the work piece.
• Cutting tool inserts according to the invention with the following composition in weight-%: 94.5 WC, 3.3 Co, 1.1 Ni, 0.6 Cr, 0.1 Mo, 0.2 VC were prepared and coated with a coating consisting of: 1.5 ⁇ m TiC, 0.5 ⁇ m Ti(C,0), 7 ⁇ m Ti(C,N) and 6 ⁇ m AI2O3.
• the TiC layer was the innermost layer closest to the cemented carbide and the AI2O3 layer was the outermost layer.

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• 1994
  • 1994-12-30 SE SE9404587A patent/SE513978C2/sv not_active IP Right Cessation
• 1995
  • 1995-12-15 EP EP95942809A patent/EP0792390B1/fr not_active Expired - Lifetime
  • 1995-12-15 AT AT95942809T patent/ATE190363T1/de not_active IP Right Cessation
  • 1995-12-15 DE DE69515503T patent/DE69515503T2/de not_active Expired - Lifetime
  • 1995-12-15 WO PCT/SE1995/001516 patent/WO1996021052A1/fr active IP Right Grant
  • 1995-12-25 IL IL11654995A patent/IL116549A/xx not_active IP Right Cessation

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