hereinafter , the disclosure will be described in detail with several embodiments in conjunction with the accompanying drawings . a femoral ball head having a multilayer shell - core composite structure , is composed of a ceramic spherical shell layer 1 including high purity and superfine alumina , an alumina - based ( niobium ) cermet interlayer 5 ( namely , transition layer ), and a niobium metal core 2 . the multilayer composite structure may have five different structures , which are illustrated in fig1 to fig5 and may be selected according to requirements of practical applications . referring to fig6 , a method for manufacturing a femoral ball head having a multilayer shell - core composite structure in the first embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include high - purity and superfine alumina powder , alumina - based ( niobium ) cermet compound powder , and niobium metal powder . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, 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 %, have a particle size ranging from 0 . 5 μm to 10 μm . in order to decrease sintering temperature and improve sintering performance , magnesium oxide ( mgo ) powder with a concentration of 0 . 25 wt . % may be added into the high - purity and superfine alumina powder , and cobalt ( co ) powder with a concentration of 3 wt . % may be added into the niobium metal powder , both of which may act as sintering aids . after preparation , the modified alumina powder , alumina - based ( niobium ) cermet compound powder and niobium metal powder 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 under a temperature of about 180 ° c . for about two and a half hours , so that a feedstock called as polyaldehydes system is obtained , which has a solid loading ( solid content ) greater than 55 vol . %. ( 2 ) by using three sets of moulds , performing injection molding successively to obtain the niobium metal core 2 , the alumina - based ( niobium ) cermet interlayer 5 , and the alumina spherical shell layer 1 , of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal . firstly , feedstocks including niobium metal polyaldehydes are injected into a core mould ( a first mould ) to obtain the niobium metal core 2 having a bore - hole 3 . then , by using the niobium metal core 2 as an insert , a complex with the alumina - based ( niobium ) cermet interlayer 5 covering the niobium metal core 2 may be obtained through injection molding in a second mould . then , by using the complex with the alumina - based ( niobium ) cermet interlayer 5 covering the niobium metal core 2 as an insert , a green body of the femoral ball head having a multilayer shell - core composite structure , which includes alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal , may be obtained through injection molding in a third mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 110 mpa to about 130 mpa , the dwell pressure may be in a range from about 70 mpa to about 80 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on an alumina spherical shell surface 4 and the bore - hole 3 formed in the niobium metal core 2 of the green body of the femoral ball head having a multilayer shell - core composite structure , which includes alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal . ( 4 ) performing catalytic debinding on the green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal in an atmosphere furnace with a temperature ranging from about 110 ° c . to about 120 ° c ., where hydrogen nitrate is used as debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding process may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - alumina ( niobium ) transition layer - niobium metal in a controlled atmosphere hot isostatic pressing ( hip ) furnace , where the sintering is performed at a temperature of about 1450 ° c ., a pressure of about 35 mpa , and the soaking time is about 1 hour , so that an alumina spherical shell layer 1 which has a relative density greater than 99 % and a hardness greater than hv1950 , an alumina ( niobium ) transition layer 5 which becomes densification and toughness and the niobium metal core 2 , may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on the alumina ceramic spherical shell surface 4 and the bore - hole 3 of the sintering body of the femoral ball head having a multilayer shell - core composite structure , which includes alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal . ( 7 ) finally , polishing the alumina ceramic spherical shell surface 4 by using sic ultrafine powder and diamond abrasive paste , to obtain the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - alumina - based ( niobium ) cermet interlayer - niobium metal , so that a smooth finished surface , and a proper dimensional coordination between the bore - hole 3 and the femoral component may be obtained . a femoral ball head having a multilayer shell - core composite structure , includes a ceramic spherical shell layer 1 including high purity and superfine alumina , a toughening ceramic interlayer 5 of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 and a toughening ceramic core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . referring to fig6 , a method for manufacturing a femoral ball head having a multilayer shell - core composite structure in the second embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include high - purity and superfine alumina powder , and compound powder of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 and compound powder of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, and 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 a particle size ranging from 0 . 5 μm to 10 μm . in order to decrease sintering temperature and improve sintering performance , magnesium oxide ( mgo ) powder with a concentration of 0 . 25 wt . % may be added into the high - purity and superfine alumina powder as sintering aids . after preparation , the modified alumina powder , compound powder of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 and compound powder of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 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 under a temperature of about 180 ° c . for about two and a half hours , so that a feedstock of polyaldehydes system , having a solid loading ( solid content ) greater than 55 vol . %, can be obtained . ( 2 ) by using three sets of moulds , performing injection molding successively to obtain the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 , the interlayer 5 of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 , and the alumina spherical shell layer 1 of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . firstly , feedstocks including zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 polyaldehydes are injected into a core mould ( a first mould ) to obtain the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 having a bore - hole 3 . then , by using the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 as an insert , a complex with the interlayer 5 of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 covering the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 may be obtained through injection molding in a second mould . then , using the complex with the interlayer 5 of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 covering the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 as an insert , a green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 , may be obtained through injection molding in a third mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 110 mpa to about 130 mpa , the dwell pressure may be in a range from about 70 mpa to about 80 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on an alumina spherical shell surface 4 and the bore - hole 3 formed in the core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 of the green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . ( 4 ) performing catalytic debinding on the green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 in an atmosphere furnace with a temperature ranging from about 110 ° c . to about 120 ° c ., where hydrogen nitrate is used as debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 in an air furnace , where the sintering may be performed at a temperature of about 1600 ° c ., and the soaking time is about 1 hour , so that an alumina spherical shell layer 1 which has a relative density greater than 99 %, a hardness greater than hv1950 , an interlayer 5 of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 which is densified and toughed and a core 2 of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 which has a fracture toughness greater than 10 mpa · m 1 / 2 , may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on the alumina ceramic spherical shell surface 4 and the bore - hole 3 of the sintering body of the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 . ( 7 ) finally , polishing the alumina ceramic spherical shell surface 4 by using sic ultrafine powder and diamond abrasive paste , to obtain the femoral ball head having a multilayer shell - core composite structure including alumina ceramic - interlayer of zro 2 ( 3y 2 o 3 )- 80 wt . % al 2 o 3 - core of zro 2 ( 3y 2 o 3 )- 20 wt . % al 2 o 3 , which has a smooth finished surface , and a proper dimensional coordination between the bore - hole 3 and the femoral component . a femoral condyle prosthesis ( one component of an artificial knee - joint ) having a multilayer shell - core composite structure , includes a ti6al4v core layer 1 , a transition layer 2 of ti6al4v - 20 vol . % al 2 o 3 , a transition layer 3 of ti6al4v - 60 vol . % al 2 o 3 , and a high - purity and superfine ceramic shell layer 4 . referring to fig6 , a method for manufacturing a femoral condyle prosthesis having a multilayer shell - core composite structure in the third embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include high - purity and superfine alumina powder , compound powder of ti6al4v - 60 vol . % al 2 o 3 , compound powder of ti6al4v - 20 vol . % al 2 o 3 , and ti6al4v powder . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, have a particle size ranging from 0 . 5 μm to 5 μm . the ti6al4v powder may have a purity greater than 99 . 5 wt %, have a particle size ranging from 10 μm to 35 μm . in order to decrease sintering temperature and improve sintering performance , magnesium oxide ( mgo ) powder with a concentration of 0 . 1 wt . % may be added into the high - purity and superfine alumina powder as sintering aids . after preparation , the modified alumina powder , compound powder of ti6al4v - 60 vol . % al 2 o 3 , compound powder of ti6al4v - 20 vol . % al 2 o 3 , and ti6al4v powder 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 under a temperature of about 180 ° c . for about two and a half hours , so that a feedstock of a polyaldehydes system is obtained , which has a solid loading ( solid content ) greater than 60 vol . %. ( 2 ) by using four sets of moulds , performing co - injection molding successively to obtain the ti6al4v core layer 1 , the transition layer 2 of ti6al4v - 20 wt . % al 2 o 3 , the transition layer 3 of ti6al4v - 80 wt . % al 2 o 3 and the high - purity and superfine alumina ceramic shell layer 4 of the femoral condyle prosthesis having a multilayer shell - core composite structure . firstly , feedstocks including ti6al4v polyaldehydes are injected into a first mould to obtain the ti6al4v core layer 1 of the femoral condyle prosthesis . then , by using the ti6al4v core layer 1 as an insert , a complex with the transition layer 2 of ti6al4v - 20 wt . % al 2 o 3 covering the ti6al4v core layer 1 may be obtained through injection molding in a second mould . then , by using the complex of the transition layer 2 of ti6al4v - 20 wt . % al 2 o 3 / the ti6al4v core layer 1 as an insert , a compound covered by the transition layer 3 of ti6al4v - 80 wt . % al 2 o 3 may be obtained through injection molding in a third mould . then , by using the complex of the transition layer 3 of ti6al4v - 80 wt . % al 2 o 3 / the transition layer 2 of ti6al4v - 20 wt . % al 2 o 3 / the ti6al4v core layer 1 as an insert , a green body of the femoral condyle prosthesis having a multilayer shell - core composite structure which is covered by the high - purity and superfine al 2 o 3 ceramic shell layer 4 , may be obtained through injection molding in a fourth mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 100 mpa to about 120 mpa , the dwell pressure may be in a range from about 70 mpa to about 85 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on the alumina shell layer 4 and the ti6al4v core layer 1 of the green body of the femoral condyle prosthesis having a multilayer shell - core composite structure . ( 4 ) performing catalytic debinding on the green body of the femoral condyle prosthesis 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 debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the femoral condyle prosthesis 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 1420 ° c ., a pressure of about 40 mpa , and the soaking time is about 1 hour , so that an alumina shell layer 4 which has a relative density greater than 99 . 5 % and a hardness greater than hv1950 , densified and toughed transition layers 2 and 3 , and a ti6al4v core layer 1 which has a high fracture toughness and has a relative density greater than 99 . 0 %, may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on the alumina shell layer 4 of the sintering body of the femoral condyle prosthesis having a multilayer shell - core composite structure . ( 7 ) then , polishing the alumina shell layer 4 by using sic ultrafine powder and diamond abrasive paste , to obtain the femoral condyle prosthesis having a multilayer shell - core composite structure , which has a smooth finished surface . an acetabulum ( one component of an artificial hip joint ) having a multilayer shell - core composite structure , includes a high - purity and superfine al 2 o 3 ceramic core layer 1 , a transition layer 2 of ti6al4v - 60 vol . % al 2 o 3 , a transition layer 3 of ti6al4v - 20 vol . % al 2 o 3 , and a ti6al4v shell layer 4 . referring to fig6 , a method for manufacturing an acetabulum having a multilayer shell - core composite structure in the fourth embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include high - purity and superfine alumina powder , compound powder of ti6al4v - 60 vol . % al 2 o 3 , compound powder of ti6al4v - 20 vol . % al 2 o 3 , and ti6al4v powder . the high - purity and superfine alumina powder may have a purity greater than 99 . 9 wt %, have a particle size ranging from 0 . 5 μm to 5 μm . the ti6al4v powder may have a purity greater than 99 . 5 wt %, have a particle size ranging from 10 μm to 35 μm . in order to decrease sintering temperature and improve sintering performance , magnesium oxide ( mgo ) powder with a concentration of 0 . 1 wt . % may be added into the high - purity and superfine alumina powder as sintering aids . after preparation , the modified alumina powder , compound powder of ti6al4v - 60 vol . % al 2 o 3 , compound powder of ti6al4v - 20 vol . % al 2 o 3 , and ti6al4v powder 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 under 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 ( solid content ) greater than 60 vol . %. ( 2 ) by using four sets of moulds , performing co - injection molding successively to obtain the high - purity and superfine al 2 o 3 ceramic core layer 1 , the transition layer 2 of ti6al4v - 60 vol . % al 2 o 3 , the transition layer 3 of ti6al4v - 20 vol . % al 2 o 3 and the ti6al4v shell layer 4 of the acetabulum having a multilayer shell - core composite structure . firstly , feedstocks including ti6al4v polyaldehydes are injected into a first mould to obtain the ti6al4v shell layer 4 . then , by using the ti6al4v shell layer 4 as an inserts , a complex with the transition layer 3 of ti6al4v - 20 wt . % al 2 o 3 covering the ti6al4v shell layer 4 may be obtained through injection molding in a second mould . then , by using the complex of the transition layer 3 of ti6al4v - 20 wt . % al 2 o 3 / the ti6al4v shell layer 4 as an inserts , a complex covered by the transition layer 2 of ti6al4v - 80 wt . % al 2 o 3 may be obtained through injection molding in a third mould . then , by using the complex of the transition layer 2 of ti6al4v - 80 wt . % al 2 o 3 / the transition layer 3 of ti6al4v - 20 wt . % al 2 o 3 / the ti6al4v shell layer 4 as an inserts , a green body of the acetabulum having a multilayer shell - core composite structure which is covered by the high - purity and superfine al 2 o 3 ceramic core layer 1 , may be obtained through injection molding in a fourth mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 100 mpa to about 120 mpa , the dwell pressure may be in a range from about 70 mpa to about 85 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on the al 2 o 3 ceramic core layer 1 and the ti6al4v shell layer 4 of the green body of the acetabulum having a multilayer shell - core composite structure . ( 4 ) performing catalytic debinding on the green body of the acetabulum 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 debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the acetabulum 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 1420 ° c ., a pressure of about 40 mpa , and the soaking time is about 1 hour , so that an alumina core layer 1 which has a relative density greater than 99 . 5 % and a hardness greater than hv1950 , transition layers 2 and 3 which are densified and toughed , and a ti6al4v shell layer 4 which has a high fracture toughness and has a relative density greater than 99 . 0 %, may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on a surface of the alumina core layer 1 of the sintering body of the acetabulum having a multilayer shell - core composite structure . ( 7 ) then , polishing a surface of the alumina core layer 1 by using sic ultrafine powder and diamond abrasive paste , to obtain the acetabulum having a multilayer shell - core composite structure , which has a smooth finished surface , and a proper dimensional coordination with a femoral ball head . a ceramic plunger having a multilayer shell - core composite structure , is composed of a zro 2 ( y + ce ) shell layer 1 , a transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), a transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and a 17 - 4ph stainless steel core spindle 4 . referring to fig6 , a method for manufacturing a ceramic plunger having a multilayer shell - core composite structure in the fifth embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include zro 2 ( y + ce ) powder , compound powder of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ) compound powder of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and 17 - 4ph stainless steel powder . the zro 2 powder may have a purity greater than 98 . 5 wt %, have a particle size ranging from 0 . 2 μm to 0 . 5 μm . the 17 - 4ph stainless steel powder may have a purity greater than 98 . 8 wt %, have a particle size ranging from 5 μm to 25 μm . in order to ensure performance , 1 . 5 % mol y 2 o 3 powder and 4 % mol ceo 2 powder may be added into the zro 2 powder as stabilizing additive , to obtain partially stabilized zro 2 ( y + ce ) powder . after preparation , the modified zro 2 ( y + ce ) powder , compound powder of 17 - 4ph stainless steel - 60 vol . % zro 2 (( y + ce ), compound powder of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and 17 - 4ph stainless steel powder 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 under 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 ( solid content ) greater than 55 vol . %. ( 2 ) by using four sets of moulds , performing co - injection molding successively to obtain the zro 2 ( y + ce ) shell layer 1 , the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and the 17 - 4ph stainless steel core spindle 4 of the ceramic plunger having a multilayer shell - core composite structure . firstly , feedstocks including 17 - 4ph stainless steel polyaldehydes are injected into a first mould to obtain the 17 - 4ph stainless steel core spindle 4 of the ceramic plunger . then , by using the stainless steel core spindle 4 as an inserts , a complex with the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ) covering the stainless steel core spindle 4 may be obtained through injection molding in a second mould . then , by using the complex of the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce )/ the stainless steel core spindle 4 as an inserts , a complex covered by the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ) may be obtained through injection molding in a third mould . at last , by using the complex of the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce )/ the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce )/ the stainless steel core spindle 4 as an inserts , a green body of the ceramic plunger having a multilayer shell - core composite structure which is covered by the superfine zro 2 ( y + ce ) ceramic shell layer 1 , may be obtained through injection molding in a fourth mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 100 mpa to about 120 mpa , the dwell pressure may be in a range from about 70 mpa to about 85 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on the zro 2 ( y + ce ) shell layer 1 and the 17 - 4ph stainless steel core spindle 4 of the green body of the ceramic plunger having a multilayer shell - core composite structure . ( 4 ) performing catalytic debinding on the green body of the ceramic plunger 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 debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the ceramic plunger 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 1350 ° c ., a pressure of about 35 mpa , and the soaking time is about 1 hour , so that a zro 2 shell layer 1 which has a relative density greater than 98 . 8 % and a hardness greater than hv1500 , transition layers 2 and 3 which are densified and toughed , and a 17 - 4ph stainless steel core spindle 4 , may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on a surface of the zro 2 ( y + ce ) shell layer 1 , and performing machining on both ends of the 17 - 4ph stainless steel core spindle 4 . ( 7 ) finally , polishing a surface of the zro 2 ( y + ce ) shell layer 1 by using sic ultrafine powder and diamond abrasive paste , to obtain the ceramic plunger having a multilayer shell - core composite structure , which has a smooth finished surface , and a proper dimensional coordination with a mantle of the ceramic plunger . a fully padded ceramic ball valve body ( including one valve body and two bonnets ) having a multilayer shell - core composite structure , is composed of a zro 2 ( y + ce ) valve liner 1 , a transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), a transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and a 17 - 4ph stainless steel valve shell 4 . referring to fig6 , a method for manufacturing a fully padded ceramic ball valve body having a multilayer shell - core composite structure in the sixth embodiment may include : ( 1 ) preparing feedstocks for powder injection molding which include zro 2 ( y + ce ) powder , compound powder of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), compound powder of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and 17 - 4ph stainless steel powder . the zro 2 powder may have a purity greater than 98 . 5 wt %, have a particle size ranging from 0 . 2 μm to 1 . 5 μm . the 17 - 4ph stainless steel powder may have a purity greater than 98 . 8 wt %, have a particle size ranging from 5 μm to 35 μm . in order to improve performance , 1 . 5 % mol y 2 o 3 powder and 4 % mol ceo 2 powder may be added into the zro 2 powder as stabilizing additive , to obtain partially stabilized zro 2 ( y + ce ) powder . after preparation , the modified zro 2 ( y + ce ) powder , compound powder of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), compound powder of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and 17 - 4ph stainless steel powder 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 under 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 ( solid content ) greater than 55 vol . %. ( 2 ) by using four sets of moulds , performing co - injection molding successively to obtain the zro 2 ( y + ce ) valve liner 1 , the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ), the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ), and the 17 - 4ph stainless steel valve shell 4 of the fully padded ceramic ball valve body having a multilayer shell - core composite structure . firstly , feedstocks including 17 - 4ph stainless steel polyaldehydes are injected into a first mould to obtain the 17 - 4ph stainless steel valve shell 4 . then , by using the stainless steel valve shell 4 as an inserts , a complex with the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce ) covering the stainless steel valve shell 4 may be obtained through injection molding in a second mould . then , by using the complex of the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce )/ the stainless steel valve shell 4 as an inserts , a complex covered by the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce ) may be obtained through injection molding in a third mould . at last , by using the complex of the transition layer 2 of 17 - 4ph stainless steel - 60 vol . % zro 2 ( y + ce )/ the transition layer 3 of 17 - 4ph stainless steel - 30 vol . % zro 2 ( y + ce )/ the stainless steel valve shell 4 as an inserts , a green body of the fully padded ceramic ball valve body having a multilayer shell - core composite structure which is covered by the superfine zro 2 ( y + ce ) valve liner 1 , may be obtained through injection molding in a fourth mould . the temperature of the injection may be in a range from about 170 ° c . to about 180 ° c ., the pressure of the injection may be in a range from about 100 mpa to about 120 mpa , the dwell pressure may be in a range from about 70 mpa to about 85 mpa , and the cooling time may be in a range from about 3 minutes to about 4 minutes . ( 3 ) if necessary , performing surface finishing on the zro 2 ( y + ce ) valve liner 1 and the 17 - 4ph stainless steel valve shell 4 of the green body of the fully padded ceramic ball valve body having a multilayer shell - core composite structure . ( 4 ) performing catalytic debinding on the green body of the fully padded ceramic ball valve body 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 debinding catalyst , nitrogen is used as debinding carrier gas , and the catalytic debinding may last for about 5 hours . ( 5 ) after being catalytic debound , sintering the green body of the fully padded ceramic ball valve body 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 1350 ° c ., a pressure of about 35 mpa , and the soaking time is about 1 hour , so that a zro 2 ( y + ce ) valve liner 1 which has a relative density greater than 98 . 8 % and a hardness greater than hv1450 , densified and toughed transition layers 2 and 3 , and a 17 - 4ph stainless steel valve shell 4 , may be obtained . ( 6 ) according to size requirements of the products , performing micro - machining on a surface of the zro 2 ( y + ce ) valve liner 1 , and if necessary , performing machining on the 17 - 4ph stainless valve shell 4 . ( 7 ) finally , polishing a surface of the zro 2 ( y + ce ) valve liner 1 by using sic ultrafine powder and diamond abrasive paste , especially a round surface of the zro 2 ( y + ce ) valve liner 1 of two bonnets , so as to obtain the fully padded ceramic ball valve body having a multilayer shell - core composite structure , which has a smooth finished surface , and a proper dimensional coordination with a valve spool of the ceramic ball valve . 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 .
a manufacturing method of a femoral condyle prosthesis having a multilayer shell - core composite structure comprises the following procedures : respectively preparing feeding material for injection forming of a core layer , a buffer layer and a shell layer , wherein the powders of feeding material of the core layer and the shell layer are selected from one or more of metallic powder , ceramic powder or toughening ceramic powder , and are different from each other , and the powder of feeding material of the buffer layer is gradient composite material powder ; layer by layer producing the blank of multilayer shell - core composite structural component by powder injection molding ; degreasing the blank ; sintering the blank to obtain the multilayer shell - core composite structural component . the femoral condyle prosthesis has the advantages of high surface hardness , abrasion resistance , uniform thickness of the shell layer , stable and persistent performance .