Abstract:
A composite includes a substrate and at least a resin composition formed on the substrate. A surface of the substrate is defined a plurality of micro-pores therein. The resin composition is coupled to the surface having the micro-pores by the resin composition filling and hardening within the micro-pores. The resin composition contains crystalline thermoplastic synthetic resins. A method for making the composite is also described.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to composites, particularly to a composite having high bonding strength and a method for making the composite. 
         [0003]    2. Description of Related Art 
         [0004]    Adhesives, for combining heterogeneous materials in the form of a metal and a synthetic resin are in demand in a wide variety of technical fields and industries, such as the automotive and household appliance fields. However, the bonding strength of the metal and resin is weak. Furthermore, adhesives are generally only effective in a narrow temperature range of about −50° C. to about 100° C., which means they are not suitable in applications where operating or environmental temperatures may fall outside of the range. Due to the above reason, other bonding methods have been applied that do not involve the use of an adhesive. One example of such methods is by forming bonds through injection molding or other similar process. However, the bonding strength of the metal and resin can be further improved. 
         [0005]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0006]    Many aspects of the disclosure can be better understood with reference to the following figures. The components in the figures are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. 
           [0007]      FIG. 1  is a cross-sectional view of an exemplary embodiment of a composite. 
           [0008]      FIG. 2  is a scanning electron microscopy view of an exemplary embodiment of a substrate being laser etched. 
           [0009]      FIG. 3  is a scanning electron microscopy view of a cross-section at the combine of the substrate and the resin composition. 
           [0010]      FIG. 4  is a scanning electron microscopy view of a surface of the substrate combining to the resin composition. 
           [0011]      FIG. 5  is a cross-sectional view of a mold of the composite shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  shows a composite  100  according to an exemplary embodiment. The composite  100  includes a substrate  11 , and at least a resin composition  13  formed on the substrate  11 . 
         [0013]    The substrate  11  may be made of metal, glass, or ceramic. The metal can be stainless steel, magnesium alloy, or copper alloy. 
         [0014]    Referring to  FIG. 2 , a plurality of micro-pores  111  are defined in a surface of the substrate  11 . The pore diameter of the micro-pores  111  may be in a range of about 1 micrometer (μm) to about 100 μm, and the pore depth of the micro-pores  111  may be in a range of about 1 μm-about 200 μm. Each two adjacent micro-pores  111  have a space between them of about 10 μm-about 200 μm. 
         [0015]    It should be understood that, the pore diameter and the pore depth of the micro-pores  111 , and the space of each two micro-pores  111  can be adjusted. 
         [0016]    In the embodiment, the micro-pores  111  are regularly distributed in an array in the surface of the substrate  11 . Alternately, the micro-pores  111  can be irregularly distributed in the surface of the substrate  11 . 
         [0017]    Referring to  FIGS. 3 and 4 , the resin composition  13  is coupled to the surface of the substrate  11  having the micro-pores  111  and fills the micro-pores  111 . That is, a portion of the resin composition  13  insert in the micro-pores  111 , which causes a locking/catching effect and strongly bonding the resin composition  13  to the substrate  11 . 
         [0018]    The resin composition  13  may be coupled to the substrate  11  by molding. The resin composition  13  may be made up of crystalline thermoplastic synthetic resins having high fluidity. In the exemplary embodiment, polyphenylene sulfide (PPS), polyamide (PA), polybutylene terephthalate (PBT), or polyethylene terephthalate (PET) can be selected as the molding materials for the resin composition  13 . The resin composition  13  can bond firmly with the substrate  11 . The molding materials can be added with some fiberglass to improve the property for molding. 
         [0019]    A method for making the composite  100  may include the following steps: 
         [0020]    The substrate  11  is provided. 
         [0021]    The substrate  11  is cleaned. The cleaning process may be carried out by dipping the substrate  11  in a water solution containing Nat The water solution may contain sodium carbonate, sodium phosphate, and sodium silicate. The sodium carbonate may have a mass concentration of about 30 g/L-about 50 g/L. The sodium phosphate may have a mass concentration of about 30 g/L-about 50 g/L. The sodium silicate may have a mass concentration of about 3 g/L-about 5 g/L. During the dipping process, the water solution may keep at about 50° C.-about 60° C. The dipping process may last about 5 min-about 15 min After that, the substrate  11  is rinsed. 
         [0022]    The substrate  11  is laser etched to form the micro-pores  111  in a surface of the substrate  11 . The laser etching process may be carried out using a laser machine having the parameters of, power: about 10 W-about 30 W, frequency: about 20 KHZ-about 60 KHZ, and step length: about 0.005 μm-about 0.1 μm. 
         [0023]    Referring to  FIG. 5 , an injection mold  20  is provided. The injection mold  20  includes a core insert  23  and a cavity insert  21 . The core insert  23  defines several gates  231 , and a first cavity  233 . The cavity insert  21  defines a second cavity  211  for receiving the substrate  11 . The substrate  11  having the micro-pores  111  is located in the second cavity  211 , and molten resin is injected through the gates  231  to coat the surface of the substrate  11  and fill the micro-pores  111 , and finally fill the first cavity  233  to form the resin composition  13 , as such, the composite  100  is formed. The molten resin may be crystalline thermoplastic synthetic resins having high fluidity, such as PPS, PA, PBT, or PET. During the molding process, the injection mold  20  keeps a temperature of about 120° C.-about 140° C. 
         [0024]    Tensile strength and shear strength of the composite  100  have been tested. The tests indicated that the shear strength of the composite  100  was about 20 MPa-about 30 MPa, and the tensile strength of the composite  100  was about 8 MPa-about 16 MPa. Furthermore, the composite  100  has been subjected to a temperature humidity bias test (72 hours, 85° C., relative humidity: 85%) and a thermal shock test (48 hours, −40° C.-85° C., 4 hours/cycle, 12 cycles total), such testing did not result in decreased the shear strength and the tensile strength of the composite  100 . 
         [0025]    The exemplary method of forming the micro-pores  111  is very effectively comparing to the conventional chemical etching, electrochemical etching or anodizing treating, and simultaneously fit for multiple materials. 
         [0026]    It is believed that the exemplary embodiment and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its advantages, the examples hereinbefore described merely being preferred or exemplary embodiment of the disclosure.