RO127024B1 - Carbonitride thin layer materials for biomedical applications - Google Patents

Abstract

The invention relates to biocompatible thin layer materials, as mono- and multilayers, based on quaternary compounds of carbonitrides of biocompatible transition metals such as Ti, Zr, Nb, Ta, or Hf used for current biomedical applications, obtained by physical vapour deposition, by magnetron sputtering or cathode arc, in reactive plasma which may contain atoms and ions of titanium, zirconium, niobium, tantalum, hafnium, nitrogen or carbon, depending on the nature of the deposited materials. According to the invention, the materials are made of the following compounds TiZrCN,TiHfCN,TiTaCN,TiNbCN, ZrHfCN, ZrTaCN, ZrNbCN, TaHfCN, TaNbCN and NbHfCN with a wide stoichiometric range 0.9 ≤ (C+N)/(M+M) ≤ 3, with a ratio of atomic concentration of elements C/N in the layer ranging between 0.5...2, with a total thickness of layer ranging between 1...4 μ m, the multilayer materials being formed of 8...120 alternating individual layers of TiZrCN,TiHfCN,TiTaCN,TiNbCN, ZrHfCN, ZrTaCN, ZrNbCN, TaHfCN, TaNbCN or NbHfCN with a thickness ranging between 20...250 nm, with the thickness ratio of individual layers ranging between 0.4...2 and with a total thickness of multilayer in the range of 1...4 μ m, adherent to substrate, critical normal forces measured in scratch adhesion testing being between 30...50 N and having a microhardness in the range of 18...32 GPa, exhibiting an average roughness lower than 10 nm and the value of the cellular viability factor ranging between 90...95% upon cytotoxicity assay.

Description

The invention relates to a multilayer carbonitrile material, made of biocompatible thin layers, based on quaternary carbonitride compounds of some metals, for biomedical applications.

At present, carbonitrides in quaternary systems (TiAICN, TiZrCN, TiVCN, TiCrCN) are known, which have been extensively analyzed in terms of their microchemical, microstructural, mechanical and tribological properties, being considered to have a special potential for application. coverage of components used in the car, chemical, electrotechnical, electronic, optical, etc. industries.

Currently the metal medical implants are made of titanium and its alloys, austenitic stainless steel and CoCr-based alloys. Against the background of the increase of life expectancy and of the active life of the population, it appears the necessity of increasing the average life of the implants in the human body, up to 20 ... 40 years. The degradation of the medical implants is mainly caused by the phenomena of wear and fatigue, as well as the rejection by the body due to cytotoxic reactions.

It is known, from US document 4269899 A, a carbide, nitride and carbonitride coating material of Hf and Ti, with at least one solid solution type (Hf / Ti) CN, and JPH 09207006 (A) has a coating material of cermet type coating, with abrasion resistance and good adhesion to the surface of the metal part, consisting of at least one carbonitride, in particular: NbTaCN type phase, with particles bound with a Co-Ni type phase (claim 1; abstract (PAJ)).

Also, JP 2009006426 (A) shows a metal tool coating material, composed of a lower coating layer, adhering to the surface of the metal tool, made of TiZrCN carbonitride, and an upper layer, of aluminum oxide.

The problem that the claimed invention aims to solve is to increase the "life" time of implants and medical devices, by covering them with a biocompatible material resistant to wear and corrosion in biological environments in the human body.

The material of quaternary carbonitrides, according to the invention, solves the mentioned technical problem by having superior biocompatible properties and increased resistance to corrosion and wear, being at least a layer of quaternary carbonitrile having the general formula Me ₁ Me ₂ CN, where Me., And Me ₂ are metals different from Ti, Zr, Nb, Ta, Hf, the plywood material having the general formula Me ₁ Me ₂ CN / Me ₃ Me ₄ CN, where Me · ,, Me ₂ , Me ₃ and Me ₄ are metals different from Ti, Zr, Nb, Ta and Hf, and consisting of

8 .. .120 alternating individual layers of carbonitrides of said type, having thicknesses of

20 .. .250 nm, with the ratio of the individual thicknesses of 0.4 ... 2 and with a total thickness of the multilayer of 1 ... 4 pm.

The superior performances of the quaternary compounds that are the subject of the invention are determined by the formation of solid equilibrium solutions, which present nanocomposite structures with nanometric (fine) granulation.

The biocompatible, mono- and multilayer material for covering implants and medical devices, according to the invention, has the following advantages:

- it has high adhesion to the substrate;

- has high micro-hardness;

- has low roughness;

- does not change the size of implants or medical devices;

- has stable mechanical and tribological properties over time;

- is resistant to the action of corrosive agencies found in the human body;

- has a low wear coefficient;

- is biocompatible, non-absorbable.

RO 127024 Β1

The material according to the invention is obtained by a physical vapor phase 1 deposition type method (magnetron sputtering, cathode arc) in a reactive plasma containing titanium, zirconium, niobium, tantalum, hafnium, nitrogen or carbon atoms and ions. depending on the nature of the 3 materials submitted. The substrate temperatures during the deposition are between 100 and 300 ° C, which does not cause structural or dimensional changes, the deposition time being between 90 and 120 min.

The invention is further described below. 7

The material according to the invention can be made either monolayer or multilayer.

The material, in monolayer type form, is made of the compounds: TiZrCN, TiHfCN, 9 TiTaCN, TiNbCN, ZrHfCN, ZrTaCN, ZrNbCN, TaHfCN, TaNbCN and NbHfCN, with a wide range of stoichiometry (N + 0.9) (Me., + Me ₂ ) <3), with a ratio of the atomic concentrations of 11 C / N elements in the layer between 0.5 and 2, with a total thickness of the layer between 1 and 4 pm. 13

An embodiment of such a monolayer material is that of a quasi-stoichiometric ((C + N) / (Zr + Hf) = 0.94) ZrHfCN layer, with a ratio of the atomic concentrations of the C / elements. N in layer equal to 1.8, with a total layer thickness of 2 µm.

The monolayer material, in another embodiment, consists of a layer of ZrNbCN, supra-17 stoichiometry ((C + N) / (Zr + Nb) = 2.9), with a ratio of the atomic concentrations of the C / N elements in layer equal to 1.1, with a total layer thickness of 3.2 µm. 19

The multilayer type material, according to the invention, consists of 8 ... 120 individual layers of alternating carbonitrides (Me ₁ / Me ₂ ) CN with (Me _1; Me ₂ ) = Ti, Hf, Zr, Ta, Nb, and Me ., * Me ₂ , of 21 TiZrCN, TiHfCN, TiTaCN, TiNbCN, ZrHfCN, ZrTaCN, ZrNbCN, TaHfCN, TaNbCN or NbHfCN, having thicknesses of 20 ... 250 nm, the ratio of the thicknesses of the individual layers in the range of 0.4. ..2 and with a total thickness of the plywood between 1 and 4 pm.

An embodiment of the multilayer material according to the invention, obtained by 25 magnetron spraying method, consists of 20 individual layers alternating with TiZrCN and TiNbCN, with a thickness of individual layers of 140 nm, with a ratio of thicknesses of 27 individual layers of 1: 1 and with a total thickness of the plywood of 2.8 pm.

The multilayer material, in another embodiment, according to the invention, is obtained by the method 29 of the cathode arc, and consists of 80 individual layers alternated by ZrNbCN and TaHfCN, with thicknesses of the individual layers of 20 and 25 nm, respectively, with a thick ratio. - 31 million of the individual layers of 0.8: 1 and with a total thickness of the multilayer of 3.6 pm.

The materials, in mono- and multilayer form, are adherent to the substrate, the normal critical forces 33 measured in the scratch test being 30 ... 50 N, and have a micro-hardness between 18 and 32 GPa. The materials have an average roughness <10 nm. 35 The materials present in the toxicity test a value of the cell viability factor in the range 90 ... 95%. 37

Claims (2)

1 Claims 3 1. Carbonitrile multilayer coating material for biomedical applications, based on quaternary carbonitride compounds (Me ₁ / Me ₂ ) CN with Me., * Me ₂ , characterized by being composed of 8. .120 individual alternating layers of carbonitrides (Me ₁ / Me ₂ ) CN with (Me _1; Me ₂ ) = Ti, Hf, Zr, Ta, Nb, having a thickness of 20 ... 250 nm, with the ratio 7 of the individual thicknesses of 0,4 ... 2 and with a total thickness of the plywood of 1 ... 4 pm. Multilayer coating material according to claim 1, characterized in that 9 that shows a good adhesion to the substrate, corresponding to a critical normal force, measured at the scratch adhesion test, of 30 ... 50 N, and has a micro-hardness of 18 ... 32 GPa, a 11 average roughness below 10 nm and a cell viability factor value of 90 ... 95% toxicity test.