BS ISO 6474-2 pdf free download

BS ISO 6474-2-2019 pdf free download.Implants for surgery — Ceramic materials Part 2: Composite materials based on a high-purity alumina matrix with zirconia reinforcement.
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 6.1);
b) chemical composition (see 6.2);
c) microstructure (see 6.3);
d) strength (see 6.4).
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 6.5).
b) fracture toughness (see 6.6);
c) hardness (see 6.7);
d) Young’s modulus (see 6.8);
e) cyclic fatigue (see 6.9);
f) accelerated ageing, including strength, cyclic fatigue and wear (see 6.10).
4.3 Material properties
To fulfil the requirements of this document, the material shall meet the limits for material properties as specified in Tables 1 and 2.
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).
6 Test methods
6.1 Bulk density
6.1.1 General
The bulk density shall be determined in accordance with ISO 18754 or EN 623-2. The benchmark of the bulk density depends on the selected composition of the composite. It is given as a relative density ρ r ≥ 99 %.
The relative density ρ r shall be calculated in accordance with Formula (1):
ρ m is the measured density, in g/cm 3 ;
ρ u is the ultimate density, in g/cm 3 .
ρ u shall be determined either by calculation or empirically.
6.1.2 Calculation of ultimate density
For the calculation of the ultimate density ρ u , the mass fraction and the density of each phase have to be
known exactly. The ultimate density is then calculated in accordance with Formula (2):
ρ i , ρ n are the densities of the individual components (alumina, zirconia, others);
m i , m n are the relative mass fractions of the components, in %.
The value ofis necessarily 100 %.
The theoretical density of each component for the application of Formula (2) shall be determined.
Impurities can be neglected for the calculation of the theoretical density if their amount has a mass fraction of ≤0,2 %.
6.1.3 Empirical determination of the ultimate density
If the ultimate density cannot be calculated to a sufficient reliability, it is recommended that the ultimate density be empirically determined in accordance with the following procedure.
a) Choose a powder batch with a representative inorganic composition.BS ISO 6474-2 pdf download.