Hunan Phohom Composite Materials Co., Ltd.

No.69,Lufeng Road, New Hi-Tech Zone
CHANGSHA,  HUNAN 
China
http://www.phohomglobal.com
  • Booth: 6443

Hunan Phohom Composite Materials Co., Ltd. is headquartered in high-tech Zone of Changsha, Hunan. It functions as a combination of production, academic and research center who focusing on the R&D, production, sales and technical services of explosion welding clad metals as well as giving solution to dissimilar metal bonding.


 Press Releases

  • 1 Preface

       Al-St transition joint plays an important role in Electrolytic Aluminum Anode part. It perfectly connected aluminum conductive bar and steel claw and solved the complex installing and repairing work caused by mechanical joint like screw, rivet, embedding or pressure joining. Meanwhile explosion clad has much less electrical resistance comparing to traditional ways which made a big difference in aluminum industry that is high electricity consuming. 

        Image I Anodic part

    2 The disadvantages of Al-St Joint in Modern Electrolytic Industry

    Because of the difference of Al and Fe properties, intermetallics will be seen in beween them during explosion especially so when temperature is more than 300℃. With that, attention must be paid to:

    i) Strictly control the production process

    During explosion, correct cladding parameters should be followed, otherwise intermetallics will be formed, thus affect the bonding strength between aluminum and steel and increase electrical resistance during actual use.

    ii) Strictly control the welding temperature

    When workers weld clad piece to aluminum bar and steel claw, they must make sure the welding temperature is less than 300℃. Numbers bigger than that intermetallics will show causing interface cracks.

    iii) Strictly control working temperature

    In the aluminum electrolytic process, carbon block of the anodic part is soaked in electrolyte which will pass the high temperature to the clad transition piece. The temperature sometimes reaches 400℃. As we know, over-heated environment is great harm to interface.

    However, titanium in between aluminum and steel, can avoid the direct cladding of these two metals and then reduce risk of intermetallics. There are many aluminum smelting factory already replaced Al-St to Al-Ti-St and received many benefits both practically and economically.

    3 Performance comparison between Al-St and Al-Ti-St 

    3.1 Production process

    Al-St and Al-Ti-St are produced using Explosion Cladding Technology. This technology is a process of metallurgical bonding between two or more dissimilar metals. Explosive is used as energy source to produce high impulse to push cladding metal to collide with the base metal at a high velocity and specific impact angle.

                         Image 2 Explosion Cladding Process

    3.2 Performance Result

    Tensile test, shear test, electrical resistance test and metallographic test are done to these two combinations . Conclusion is described as follows:

    3.2.1 Mechanical test

    To do the test, samples were first taken from Al-St and Al-Ti-St plate and then placed in resistance glove for 24 hours storing under temperature 300℃, 400℃ and 500℃. After cooling, tensile test and shear test were done in room temperature. Test samples are showed in Image 3 and 4; Test result are demonstrated in table 1 and 2.

    Table 1 Tensile test result under different temperature

               Combination

    Temperature

    Al-St

    Al-Ti-St

    未处理

    147MPa

    181MPa

    300℃/24h

    123MPa

    182 MPa

    400℃/24h

    79 MPa

    164MPa

    500℃/24h

    <20 MPa

    119MPa

           Image 3 Tensile test sample

    With temperature went up, tensile strength of Al-St dropped dramatically. When temperature reached 400℃, strength was only 50% than that of nature state and no obvious strength showed when temperature run to 500℃. However Al-Ti-St had totally different situation, tensile strength remained 90% under 400℃ and 110MPa strength after 500℃ treatment.

    Table 2  Shear test result under different temperature

               Combination

    Temperature

    Al-St

    Al-Ti-St

    Al-Ti

    Ti-St

    before test

    92 MPa

    95MPa

    245MPa

    300℃/24h

    87 MPa

    96MPa

    251MPa

    400℃/24h

    75 MPa

    89 MPa

    239MPa

    500℃/24h

    <20 MPa

    85 MPa

    221MPa

     

     

    Image 3 Shear test sample

    Shear test result showed an alike story that Al-St strength was only 80% than that of the one before test while Al-Ti-St remained 95% both after 400℃ treatment.

    It thus can be seen that Al-Ti-St has much better mechanical performance under high temperature than combination Al-St, therefore it is strongly recommended in aluminum industry where usually high temperature environment.

    3.2.2 Electrical performance

    After heat treatment, electrical resistance was made to samples. (Sample dimensions 5×5×52mm; current 5A) test result are showed in table 2

    Table3  Resistance test result under different temperature

                 combination

    Temperature

    Al-St

    Al-Ti-St

    voltage drop/V

    electrical resistance /μΩ

    voltage drop/V

    electrical resistance/μΩ

    before test

    0.318×10-3

    63.6

    0.344×10-3

    68.8

    300℃/1day

    0.385×10-3

    77.0

    0.345×10-3

    69.0

    400℃/1day

    0.426×10-3

    85.2

    0.351×10-3

    70.2

    500℃/1day

    0.454×10-3

    90.8

    0.375×10-3

    75.0

    As we all know, titanium has high electrical resistance, so it is reasonable that the resistance of Al-Ti-St is higher than Al-St under natural state, however from the table we can see when temperature increase, the resistance of Al-St increased 34% accordingly but Al-Ti-St remained almost the same as regular temperature.


 Products

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