hereinafter , the disclosure will be described in detail with several embodiments in conjunction with the accompanying drawings . fig1 and fig2 schematically illustrate exploded perspective views of two kinds of artificial hip joints composed of multilayer shell - core composite structural components according to embodiments of the present disclosure . both of the two kinds of artificial hip joints include an artificial acetabulum 1 having a multilayer shell - core composite structure and an artificial femoral ball head 2 having a multilayer shell - core composite structure . the artificial acetabulum 1 has two kinds of structures : multiple - head convex screw thread ( shown in fig1 ) or multiple - head concave screw thread ( shown in fig2 ) disposed on a surface of a shell 1 - 4 , which may be selected based on actual requirements . the artificial acetabulum 1 and the artificial femoral ball head 2 constitute a movable joint , thanks to a concave sphere of an artificial acetabular liner layer 1 - 1 and a sphere of an artificial femoral ball head shell layer 2 - 1 being fit slidingly . the concave sphere of the artificial acetabular liner layer 1 - 1 and the sphere of the artificial femoral ball head shell layer 2 - 1 are processed into mirror surfaces and can slide freely relative to each other . when the artificial hip joint is implanted , the artificial acetabulum 1 is fixed at the location of the original acetabulum of the human body , and the artificial femoral ball head 2 is fixed at a neck of the artificial femoral stem which is matched with femoral medullary cavity . then , the artificial femoral ball head 2 is mounted in the artificial acetabular liner layer 1 - 1 , so as to achieve physical function of the artificial hip joint . an artificial acetabulum having a multilayer shell - core composite structure in an artificial hip joint composed of multilayer shell - core composite structural components , includes an acetabular liner layer 1 - 1 made of high - purity and superfine alumina ceramic , a transition layer 1 - 2 made of alumina - based ( 25 vol % niobium ) cermet , a transition layer 1 - 3 made of alumina - based ( 65 vol % niobium ) cermet , and a metal shell layer 1 - 4 made of niobium porous . multiple - head convex screw thread ( shown in fig3 ) or multiple - head concave screw thread ( shown in fig4 ) may be disposed on a surface of the shell layer 1 - 4 , which may be selected based on actual requirements . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . the niobium metal powder may have a purity greater than 99 . 8 wt %, and have a particle size ranging from 0 . 5 μm to 20 μm . all of the acetabular liner layer 1 - 1 made of high - purity and superfine alumina ceramic , the transition layer 1 - 2 made of alumina - based ( 25 vol % niobium ) cermet , the transition layer 1 - 3 made of alumina - based ( 65 vol % niobium ) cermet , and the metal shell layer 1 - 4 made of niobium porous are injection molded into one piece layer by layer using multi - material powder co - injection molding . the liner layer 1 - 1 , the transition layers 1 - 2 and 1 - 3 , and the shell layer 1 - 4 are overlapped parallelly at the edges of an acetabulum opening . an artificial acetabulum having a multilayer shell - core composite structure in an artificial hip joint composed of multilayer shell - core composite structural components , includes an acetabular liner layer 1 - 1 made of high - purity and superfine alumina ceramic , a transition layer 1 - 2 made of ti6al4v - 60 vol . % al 2 o 3 , a transition layer 1 - 3 made of ti6al4v - 20 vol . % al 2 o 3 , and a shell layer 1 - 4 made of ti6al4v . multiple - head convex screw thread ( shown in fig5 ) or multiple - head concave screw thread ( shown in fig6 ) may be disposed on a surface of the shell layer 1 - 4 , which may be selected based on actual requirements . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . the ti6al4v powder may have a purity greater than 99 . 0 wt %, and have a particle size ranging from 5 μm to 25 μm . all of the acetabular liner layer 1 - 1 made of high - purity and superfine alumina ceramic , the transition layer 1 - 2 made of ti6al4v - 60 vol . % al 2 o 3 , the transition layer 1 - 3 made of ti6al4v - 20 vol . % al 2 o 3 , and the shell layer 1 - 4 made of ti6al4v are injection molded into one piece layer by layer using multi - material powder co - injection molding . the acetabular liner layer 1 - 1 made of high - purity and superfine alumina ceramic fully covers the transition layers 1 - 2 and 1 - 3 and the shell layer 1 - 4 . an artificial femoral ball head having a multilayer shell - core composite structure in an artificial hip joint composed of multilayer shell - core composite structural components , includes a spherical shell layer 2 - 1 made of high - purity and superfine alumina ceramic , a transition layer 2 - 5 made of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 toughened ceramic , and an inner core 2 - 2 made of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 toughened ceramic . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . the zro 2 powder may have a purity greater than 99 . 8 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . all of the spherical shell layer 2 - 1 made of high - purity and superfine alumina ceramic , the transition layer 2 - 5 made of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 toughened ceramic , and the inner core 2 - 2 made of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 toughened ceramic are injection molded into one piece layer by layer using multi - material powder co - injection molding . five kinds of multilayer shell - core composite structures are illustrated in fig7 to fig1 , which may be selected based on actual requirements . referring to fig1 , a method for manufacturing an artificial femoral ball head according to an embodiment of the present disclosure may include : ( 1 ) preparing feedstocks for powder injection molding which include high - purity and superfine aluminia powder , toughened ceramic compound powder of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 , and toughened ceramic powder of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . the prepared powders are mixed with polyoxymethylene resin binder ( 89 wt . % polyformaldehyde , 5 wt . % high density polyethylene and 6 wt . % other binding assistant agent ). the mixture is then mixed at a temperature of about 180 ° c . for about two and a half hours , so that a polyaldehydes system is obtained , which has a solid loading greater than 55 vol . %. ( 2 ) by using three sets of moulds , performing injection molding successively to obtain an inner core , a transition layer and a spherical shell layer , so as to obtain a green body of the femoral ball head having a multilayer shell - core composite structure . the temperature of the injection may be in a range from about 170 ° c . to 180 ° c ., the pressure of the injection may be in a range from about 110 mpa to 130 mpa , the dwell pressure may be in a range from about 70 mpa to 80 mpa , and the cooling time may be in a range from about 3 minutes to 4 minutes . ( 3 ) if necessary , performing surface finishing on a surface of the spherical shell and a bore - hole in the inner core of the green body of the femoral ball head having a multilayer shell - core composite structure . ( 4 ) performing catalytic debinding on the green body of the femoral ball head having a multilayer shell - core composite structure in an atmosphere furnace with a temperature ranging from about 110 ° c . to about 120 ° c ., where hydrogen nitrate is used as a debinding catalyst , nitrogen is used as a debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytically debound , sintering the green body of the femoral ball head having a multilayer shell - core composite structure in a controlled atmosphere hot isostatic pressing ( hip ) furnace , where the sintering may be performed at a temperature of about 1450 ° c ., a pressure of about 35 mpa , and the soaking time is about 1 hour . ( 6 ) according to size requirements of the products , performing micro - machining on the surface of the spherical shell and the bore - hole of the sintered body . ( 7 ) then , polishing the surface of the spherical shell by using sic ultrafine powder and diamond abrasive paste , to obtain the femoral ball head having a multilayer shell - core composite structure , which has a smooth finished surface , and a proper dimensional coordination between the bore - hole and the femoral stem . an artificial femoral ball head having a multilayer shell - core composite structure in an artificial hip joint composed of multilayer shell - core composite structural components , includes a spherical shell layer 2 - 1 made of high - purity and superfine alumina ceramic , a transition layer 2 - 5 made of al 2 o 3 - 30 vol % ( ce - tzp ) toughened ceramic , and an inner core 2 - 2 made of al 2 o 3 - 70 vol % ( ce - tzp ) toughened ceramic . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . the zro 2 powder may have a purity greater than 99 . 8 wt %, and have a particle size ranging from 0 . 5 μm to 10 μm . all of the spherical shell layer 2 - 1 made of high - purity and superfine alumina ceramic , the transition layer 2 - 5 made of al 2 o 3 - 30 vol % ( ce - tzp ) toughened ceramic , and the inner core 2 - 2 made of al 2 o 3 - 70 vol % ( ce - tzp ) toughened ceramic are injection molded into one piece layer by layer using multi - material powder co - injection molding . five kinds of multilayer shell - core composite structures are illustrated in fig7 to fig1 , which may be selected based on actual requirements . although the present disclosure has been disclosed above with reference to preferred embodiments thereof , it should be understood that the disclosure is presented by way of example only , and not limitation . those skilled in the art can modify and vary the embodiments without departing from the spirit and scope of the present disclosure .
an artificial acetabulum having a multilayer shell - core composite structure includes a ceramic acetabular liner , a transition layer and an acetabular shell . the acetabular shell is made of a porous metal , a porous alloy or a porous toughened ceramic ; the ceramic acetabular liner is made of a ceramic material ; and the transition layer is made of a composite material comprising materials of the acetabular shell and the ceramic acetabular liner . the artificial acetabulum is manufactured through sintering a green body of successively stacked layers of the ceramic acetabular liner , the transition layer and the acetabular shell , and the green body of successively stacked layers is obtained through a powder co - injection molding process . the ceramic acetabular liner of the artificial acetabulum has a high rigidness , corrosion - proof and wear - proof performance . the acetabular shell of the artificial acetabulum has a high toughness and shockresistant performance .