ISO 6474-2:2019 pdf free.Implants for surgery一Ceramic materials -Composite materials based on a high- purity alumina matrix with zirconia reinforcement.
3 Terms and Definitions
No terms and definitions are listed in this document.
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4 Classification
4.1 Material types
The material shall be classified as either Type X or Type S:
— Type X: extra-high strength;
— Type S: standard high strength.
Ceramic materials of Type X are intended for applications where extra-high strength of the material is required (e.g. thin-walled bearings for hip or knee joint replacements).
Ceramic materials of Type S are intended for applications where an improved strength in comparison to pure alumina is recommended (e.g. standard hip joint replacement).
In particular, the strengths of ceramic materials of type X and type S are higher than for materials according to type A as defined in ISO 6474-1.
4.2 Test categories
4.2.1 General
The required tests shall be distinguished in category 1 and category 2.
4.2.2 Category 1: required tests representative for periodical production control
The following tests shall be performed for periodical production control:
a) bulk density (see i); b) chemical composition (see 2); c) microstructure (see 3); d) strength (see £4). 4.2.3 Category 2: required tests representative for the general material specification
The manufacturer shall define the general material specification. In addition to all the tests listed in 4.2.2, the following tests shall be performed for qualification of the material specification:
a) radioactivity (see £5). b) fracture toughness (see ); c) hardness (see 7);
5 Preparation of specimens
Specimens shall be produced in a similar way to the regular production of implants. The same feedstock and comparable shaping technology (e. g. axial pressing, isostatic pressing), high-temperature process (e. g. sintering, hot isostatic pressing) and hard machining (e. g. grinding, polishing) shall be applied. The shaping and surface finishing of the specimens shall be accomplished according to the requirements of the test.
The manufacturer shall declare and justify that the production of the specimens is equivalent to the regular production.
Finished products or portions of them can be used for the evaluation of material properties. However, due to geometric restrictions and to the risk of damage during specimen preparation, it is not recommended to produce specimens as portions of finished products for evaluation of the following
material properties: – strength (6.4); -fracture toughness (6.6); – cyclic fatigue (6.9).
Produce at least 10 test pieces by sintering and hot isostatic pressing. Choose the sintering and hot isostatic pressing conditions according to the experience of the manufacturer in order to achieve the highest possible density. Analyse the microstructure after this process for any evidence of residual pores. If no pores can be detected, measure the density according to Iso 18754. The outer surface of the test pieces shall be ground or polished. Round off the density of each test piece to two decimal places (x,xxg/cm3). Declare the highest value of all individual density values as the ultimate density. ISO 13383-1 or EN 623-3 shall be applied for the determination of microstructure. The linear intercept grain size of the alumina grains and zirconia grains shall be determined. The grain size determination of other phases is not required. Five test specimens shall be used for the determination of microstructure. NOTE The linear intercept method reveals a nominal average grain size for the selected position of the micrograph, not the distribution of the size of individual grains.ISO 6474-2 pdf download.