Seco Tools Ab

Sandvik Ab

Sakari A Ruppi

Lennart Karlsson

Jenni Zackrisson

Andreas J Larsson

Anna Sandberg

Anette Sulin

Silvia Dahlund

Edward Laitila

Jan Qvick

Rolf Olofsson

Lena Pettersson

Lena Petersson

An &#x3b1;-AlOcoated cutting tool insert combining a cemented carbide with a binder phase enriched surface zone and a textured &#x3b1;-AlO-layer is disclosed. The &#x3b1;-AlOlayer has a thickness ranging from about 2-9 &#x3bc;m and is composed of columnar grains having a length/width ratio from about 2-12. It is characterized by a strong (104) growth texture and by low intensity of the (012), (110) and (113) diffraction peaks. The textured &#x3b1;-AlOis preferably deposited on an MTCVD Ti(C,N) layer having a thickness from about 2-10 &#x3bc;m. When the alumina layer is the uppermost layer, it may be wet-blasted to an Rvalue of &#x3c;about 1 &#x3bc;m, giving the tool a black and shiny appearance.

Alumina coated grade

The present invention relates to a coated cutting tool insert comprising a substrate and a coating to be used in metal machining. The hard and wear resistant coating exhibits an excellent adhesion to the substrate covering all functional parts thereof. The coating is composed of one or more refractory layers of which at least one layer is &#x3b1;-AlOshowing a strong growth texture along &#x3c;001&#x3e;. The &#x3b1;-AlOlayer has a thickness ranging from 1 to 20 &#x3bc;m and is composed of columnar grains with a length/width ratio of 2 to 15. The layer is characterized by a strong (006) diffraction peak, measured using XRD, and by low intensity of (012), (104), (113) (024) and (116) diffraction peaks. The &#x3c;001&#x3e; textured &#x3b1;-AlOlayers is deposited in a temperature range of 750-1000&#xb0; C. The texture is controlled by a specific nucleation procedure combined with the use of sulphur- and fluorine containing dopants.

Alumina layer with enhanced texture

A refined method to produce textured &#x3b1;-AlOlayers in a temperature range of 750-1000&#xb0; C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The &#x3b1;-AlOlayer is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminum content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step composed of short pulses and purges of Ti-containing and oxidizing steps. The &#x3b1;-AlOlayer has a thickness ranging from 1 to 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from 2 to 15, preferably 6 to 10. The layer is characterized by a strong (110) growth texture, measured using XRD, and by the low intensity of (012), (104), (113), (024) and (116) diffraction peaks.

Enhanced alumina layer with texture

Wear resistance of the prior-art Ti(C,N) layers can be considerably enhanced by optimizing the grain size and microstructure. This invention describes a method to obtain controlled, fine, equiaxed grain morphology in Ti(C,N) layers produced using moderate temperature CVD (MTCVD). The method includes the step of doping using CO, CO, ZrC1and A1C1or combinations of these to control the grain size and shape. Doping has to be controlled carefully in order to avoid nanograined structures and oxidization. Doping is further controlled to produce grain size that is from about 50 to about 300 nm, preferably from about 50 to about 150; a lack of any strong preferred growth orientation; and a length-to-width ratio (L/W) of less than 3 and only with a slight to moderate XRD line broadening.

Method of forming a coating with controlled grain size and morphology for enhanced wear resistance and toughness

The present invention relates to a coated cutting tool insert and a texture-hardened &#x3b1;-AlOlayer to be used in metal machining. The alumina layer is characterized by the improved toughness and it adheres to the substrate covering all functional parts thereof. The coating is composed of one or more refractory layers of which at least one layer is a texture-hardened &#x3b1;-AlOhaving a thickness ranging from 2 to 20 &#x3bc;m being composed of columnar grains with a length/width ratio of 2 to 12. The &#x3b1;-AlOexhibits a strong (0006) diffraction peak. The improved wear resistance and toughness can be obtained when the texture coefficient (TC) for the (0006) reflection is larger than 1.33 ln h+2, where h is the &#x3b1;-AlOlayer thickness and when the surface of the &#x3b1;-AlOlayer is wet-blasted to an R-value &#x3c;1 &#x3bc;m. The alumina layer with a strong (0001) texture is applied on Binder phase enriched cemented carbide substrates. This combination contributes to enhanced wear resistance and toughness.

Texture-hardened alpha-alumina coated tool

A new and refined method to produce &#x3b1;-AlOlayers in a temperature range of from about 750 to about 1000&#xb0; C. with a controlled growth texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The &#x3b1;-AlOlayer of the present invention is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step being composed of short pulses and purges consisting of Ti/Al-containing pulses and oxidising pulses. The &#x3b1;-AlOlayer according to the present invention has a thickness ranging from about 1 to about 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from about 2 to about 12, preferably from about 4 to about 8. The layer is characterized by a strong (104) growth texture, measured using XRD, and by low intensity of (012), (110), (113), (024) and (116) diffraction peaks.

Alumina layer with controlled texture

A method of forming a coated body composed of small columnar crystals coated using the MTCVD process. Wear resistance of the prior-art Ti(C,N) layers can be considerably enhanced by optimising the grain size and microstructure. Considerably better wear resistance in, for example in many carbon steels, can be obtained by modifying the grain size and morphology of prior art MTCVD Ti(C,N) coatings. The method includes a step of doping by using CO, CO, ZrCl, HfCland AlClor combinations of these to ensure the control of the grain size and shape. Doping has to be controlled carefully in order to maintain the columnar structure and also in order to avoid nanograined structures and oxidisation. The preferred grain size should be in the sub-micron region with the grain width of from about 30 to about 300 nm. The length to width ratio should be more than 5, preferably more than 10 and the coating should exhibit a strong preferred growth orientation along 422 or 331. The XRD line broadening should be weak.

Method of forming a layer with controlled grain size and morphology for enhanced wear resistance

A refined method to produce textured &#x3b1;-AlOlayers in a temperature range of from about 750 to about 1000&#xb0; C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The &#x3b1;-AlOlayer is deposited on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step being composed of short pulses and purges consisting of Ti/Al-containing pulses and oxidizing pulses. The &#x3b1;-AlOlayer according to this invention has a thickness ranging from about 1 to about 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from about 2 to about 12, preferably from about 5 to about 8. The layer is characterized by a strong (116) growth texture, measured using XRD, and by low intensity of (012), (110), (113) (024) and diffraction peaks.

A refined method to produce textured &#x3b1;-AlOlayers in a temperature range of from about 750 to about 1000&#xb0; C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The &#x3b1;-AlOlayer is deposited on a bonding layer of (Ti,Al) (C,O,N) with increasing aluminium content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step being composed of short pulses and purges consisting of Ti/Al-containing pulses and oxidizing pulses. The &#x3b1;-AlOlayer according to this invention has a thickness ranging from about 1 to about 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from about 2 to about 12, preferably from about 5 to about 8. The layer is characterized by a strong (116) growth texture, measured using XRD, and by low intensity of (012), (110), (113) (024) and diffraction peaks.

A refined method to produce textured &#x3b1;-AlOlayers in a temperature range of 750-1000&#xb0; C. with a controlled texture and substantially enhanced wear resistance and toughness than the prior art is disclosed. The &#x3b1;-AlOlayer is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step composed of short pulses and purges of Ti-containing and oxidizing steps. The &#x3b1;-AlOlayer has a thickness ranging from 1 to 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from 2 to 15, preferably 6 to 10. The layer is characterized by a strong (110) growth texture, measured using XRD, and by the low intensity of (012), (104), (113), (024) and (116) diffraction peaks.

Wear resistance of the prior-art Ti(C,N) layers can be considerably enhanced by optimising the grain size and microstructure. This invention describes a method to obtain controlled, fine, equiaxed grain morphology in Ti(C,N) layers produced using moderate temperature CVD (MTCVD). The control of the grain size and shape can be obtained by doping using CO, CO, ZrCland AlClor combinations of these. Doping has to be controlled carefully in order to avoid nanograined structures and oxidisation. This kind of coatings shows new enhanced wear properties. The fine grain size together with equiaxed grain morphology enhances the toughness of the coating with at least maintained wear resistance, which can be seen especially in sticky steels like stainless steels. The optimum grain size is from about 50 to about 300 nm, preferably from about 50 to about 150. The coatings according to this invention are characterised by the lack of any strong preferred growth orientation, the length-to-width ratio (L/W) around 1 and only with a slight to moderate XRD line broadening.

Coating with controlled grain size and morphology for enhanced wear resistance and toughness

The present invention introduces a new and refined method to produce &#x3b1;-AlOlayers with substantially better wear resistance and toughness than the prior art. The &#x3b1;-AlOlayer of the present invention is formed on a bonding layer of (Ti,Al)(C,O,N) with increasing aluminium content towards the outer surface. Nucleation of &#x3b1;-AlOis obtained through a nucleation step being composed of both aluminising and oxidisation steps. The &#x3b1;-AlOlayer according to this invention has a thickness ranging from 1 to 20 &#x3bc;m and is composed of columnar grains. The length/width ratio of the alumina grains is from 2 to 12, preferably 5 to 9. The layer is characterised by a strong (012) growth texture, measured using XRD, and by the almost total absence (104), (110), (113) and (116) diffraction peaks.

Enhanced alumina layer produced by CVD

Wear resistance of the prior-art Ti(C,N) layers can be considerably enhanced by optimizing the grain size and microstructure. Considerably better wear resistance in, for example in many carbon steels, can be obtained by modifying the grain size and morphology of prior art MTCVD Ti(C,N) coatings. The improved coating is composed of small columnar crystals. Doping by using CO, CO, ZrCl, HfCland AlClor combinations of these can ensure the control of the grain size and shape. Doping has to be controlled carefully in order maintain the columnar structure and also in order to avoid nanograined structures and oxidization. The preferred grain size should be in the sub-micron region with the grain width of from about 30 to about 300 nm. The length to width ratio should be more than 5, preferably more than 10 and the coating should exhibit a strong preferred growth orientation along 422 or 331. The XRD line broadening should be weak.

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Fagersta, Sweden

Sakari A Ruppi