Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by the National Medical Products Administration of People’s Republic of China.
This standard is under the jurisdiction of National Technical Committee on Implants for Surgery and Orthopaedic Devices of Standardization Administration of China (SAC/TC 110).
Surgical implants - Anodizing oxide layers on titanium and titanium alloys - General requirements
1 Scope
This standard specifies the terms and definitions, performance requirements and test methods of anodizing oxide layers on titanium and titanium alloys for surgical implants.
This standard is applicable to the anodizing oxide layers due to oxidation reaction on the surface of titanium and titanium alloy products which serve as the anodes in the corresponding electrolyte under an external electric field according to the electrolysis principle.
This standard is not applicable to surfaces treated by anodizing oxidation process for the purpose of adding non-matrix elements and various surfaces modified by physical or other chemical methods.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) applies.
GB/T 4340.1 Metallic materials - Vickers hardness test - Part 1: Test method
GB/T 6463 Metallic and other non-organic coatings; Review of methods of measurement of thickness
GB/T 16886.1 Biological evaluation of medical devices - Part 1: Evaluation and testing within a risk management process
GB/T 16886.5 Biological evaluation of medical devices - Part 5: Tests for in vitro cytotoxicity
GB/T 17359 Microbeam analysis - Quantitative analysis using energy dispersive spectrometry
YY/T 1552-2017 Implants for surgery - Measurements of open-circuit potential to assess corrosion behaviour of metallic implantable materials and medical devices over extended time periods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
anodizing oxidation
process of forming an oxide layer on the anode surface of a metal and its alloy by electrolysis
3.2
anodizing oxide layer
oxide layer formed on the surface of a metal and its alloy during electrochemical anodizing oxidation process, with protective, identification or other properties
3.3
anodizing titanium and titanium alloy
electrochemical oxidation of titanium and titanium alloy, i.e. the process of forming an oxide layer on the surface under specific process conditions with titanium and titanium alloy as anodes under the action of an external electric field in corresponding electrolyte
3.4
color anodizing layer
anodizing oxidation process designed to identify products rather than improve their mechanical properties. An oxide layer with a thickness of tens of nanometers to hundreds of nanometers and the main component of titanium oxide may be formed on the surface of titanium and titanium alloys in the process of anodizing oxidation. The oxide layer is a transparent interference film and can strongly reflect and refract light. The color displayed by the color anodizing layer of titanium and titanium alloy depends on the thickness of the oxide layer and the principle of interference.
3.5
dark gray anodizing layer
anodizing oxidation process designed to improve product performance. In the process of electrochemical anodizing oxidation of titanium and titanium alloy, a dense oxide layer is formed on the surface of titanium and titanium alloy by electrochemical reaction with special electrolyte, and the visual color of the oxide layer is dark gray.
3.6
critical scratch load, Lc
normal load applied on the anodizing oxide layer surface to produce a specified or specific form of damage or failure in the scratch test
4 Requirements
4.1 Color and color difference
The surface color of color anodizing products shall be uniform. The color shall be determined by a standard color plate agreed by the supplier and the demander, or may also be checked according to the upper and lower limit samples, or the allowable deviation of the color shall be determined by an instrument agreed by the supplier and the demander.
4.2 Thickness of dark gray anodizing layer
For dark gray anodizing products, the thickness range of anodizing oxide layer shall be agreed by the supplier and the demander.
4.3 Open circuit potential of dark gray anodizing products
The dark gray anodizing products shall be subject to open circuit potential test, and their average open circuit potential shall be higher than the open circuit potential of products without anodizing oxidation treatment specified by the enterprise.
4.4 Mechanical property
4.4.1 Scratch resistance: The dark gray anodizing products shall be subject to surface scratch test, and the manufacturer shall specify the scratch depth under constant load and the critical scratch load under gradually increasing load.
Note: Satisfactory test results may not be obtained due to some reasons of the substrate. The test personnel shall design the test scheme of the product according to the product characteristics.
4.4.2 Hardness: The dark gray anodizing products shall be subject to Vickers hardness test with small load, and the average hardness shall be higher than the hardness of the substrate.
4.4.3 For the samples that cannot meet the hardness test conditions, the mechanical properties specified in the standard may be compared with those specified in the corresponding standards, and the average value of mechanical properties shall be higher than that of mechanical properties of the substrate.
4.5 Qualitative analysis of elements on anodizing oxide layer surface
Qualitative analysis of elements on the surface of anodizing oxidation products shall be conducted by scanning electron microscope and energy disperse spectrometer.
If there are other elements inconsistent with the base material, the manufacturer shall verify the process and give a reasonable explanation. If the manufacturer can't give a reasonable explanation, the biosafety shall be evaluated according to the requirements of GB/T 16886.1.
4.6 Cytotoxicity
The cytotoxicity shall be evaluated according to product characteristics.
5 Test methods
5.1 Color and color difference
Place the samples on the same plane, and observe the color of the samples with normal or corrected vision in the scattered sunlight in a direction nearly perpendicular to the sample. The color shall be within the allowable range of the color plate or upper and lower limit provided by the enterprise.
5.2 Thickness of anodizing oxide layer
The thickness of anodizing oxide layer shall be tested according to the method specified in GB/T 6463 or recognized methods (existing ISO methods or methods recommended by national standards).
5.3 Open circuit potential of dark gray anodizing products
The dark gray anodizing products shall be tested according to the method specified in YY/T 1552-2017. The open circuit potential of at least three samples shall be tested, and their average values shall meet the requirements of 4.3.
Note: The open circuit potential will change over a long period of time. In order to ensure that the samples reach a relatively steady state in the test solution, an appropriate open circuit potential test cycle shall be selected. According to different test conditions, the reaction on the sample surface in contact with the test solution reaches equilibrium and the potential becomes more stable usually after the sample is immersed for 1h or 2h. Therefore, it is suggested to determine the open circuit potential test cycle of dark gray anodizing products according to the test requirements. It is a choice to stop the test after recording the open circuit potential for 3h and when the potential change rate is less than 3mV/min, and record the open circuit potential value at this time.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements
5 Test methods
Annex A (Normative) Test method for scratch resistance
